Hydrophobic finish compositions with extended flow time retention and building products made thereof

ABSTRACT

Disclosed are hydrophobic finish compositions and cementitious articles made with the hydrophobic finish compositions. In some embodiments, the article is a waterproof gypsum panel surface reinforced with inorganic mineral fibers that face a flexible and hydrophobic cementitious finish possessing beneficial waterproofing properties. These waterproof gypsum panels have many uses, such as, tile backer board in wet or dry areas of buildings, exterior weather barrier panel for use as exterior sheathing, interior wall and ceiling, and roof cover board having water durability and low surface absorption. The flexible and hydrophobic cementitious finish can include fly ash, film-forming polymer, preferably silane compound (e.g., alkyl alkoxysilane), an extended flow time retention agent including either one or more carboxylic acids, salts of carboxylic acids, or mixtures thereof, and other optional additives. Preferably a pre-coated non-woven glass fiber mat is employed to provide the inorganic mineral fibers for the surface reinforcement.

CROSS-REFERENCE TO RELATED APPLICATIONS

This claims priority from U.S. provisional patent application No.62/133,216, filed Mar. 13, 2015 and U.S. patent application Ser. No.14/973,330 filed Dec. 17, 2015, each incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to hydrophobic finish compositions andarticles made with the said hydrophobic finish compositions. In someembodiments, the article is an inorganic cementitious panel that issurface reinforced with a fibrous mat coated with a hydrophobic finishpossessing beneficial waterproofing properties. The hydrophobic finishcomposition comprises fly ash, film-forming polymer, and an extendedflow time retention agent comprising one or more carboxylic acids, saltsof carboxylic acids, or mixtures thereof, and preferably the hydrophobicfinish compositions of the invention also comprises silane. Thehydrophobic finish composition described herein could be used by itselfor with other substrates or products in applications where it isimportant to have waterproofing properties. To improve water resistanceand permit use of relatively less hydrophobic finish composition, thefibrous mat for surface reinforcing the inorganic cementitious panel ispre-coated with a polymer.

BACKGROUND OF THE INVENTION

In construction applications it is important to protect buildingcomponents from water intrusion and moisture related damage.Cementitious articles, such as gypsum board and cement board, are usefulin a variety of applications, some of which require a degree of waterresistance. Thus, for such applications, it is often desirable to use acementitious article faced with a glass or polymer-based fiber matinstead of paper. It also is advantageous to use additives in thecementitious core that improve the water resistance of the core materialitself. However, to improve water resistance the mat-faced gypsum boardor cement board comprising, consisting of, or consisting essentially ofgypsum-based core and fibrous mat is provided with a coating ofhydrophobic finish. The fiber mat has an inner surface facing at leastone face of the gypsum-based core and an outer surface opposite theinner surface. The hydrophobic finish faces the outer surface of themat. The major components of the hydrophobic finish are Class C fly ashto promote bonding of finish materials, film-forming polymer andpreferably silane compound for water resistance.

However, a drawback of the hydrophobic finish is that it can stiffen tooquickly and interfere with operation of industrial production equipmentsuch as roller coaters.

Stiffening of the hydrophobic finish coating leads to buildup on theroller coater and coating delivery system, which makes extendedproduction run difficult. Further, buildup of coating material on therollers makes it difficult to produce uniform coating with satisfactoryapplication rate and product appearance.

It would also be desirable if the hydrophobic finish coating was capableof being applied to a substrate both in industrial manufacturingoperations as well as in the field on construction job sites.

It would also be desirable to achieve improved water resistance withless hydrophobic finish coating.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the invention provides a hydrophobic finish compositioncomprising;

-   -   (i) hydraulic component comprising fly ash, preferably the fly        ash comprises Class C fly ash, wherein the fly ash more        preferably comprises Class C fly ash in an amount from about 50%        to about 85% by weight of the finish composition on a water        inclusive basis;    -   (ii) film-forming polymer; and    -   (iii) an extended flow time retention agent comprising at least        one member of the group consisting of carboxylic acids, salts of        carboxylic acids, and mixtures thereof.

Preferably, the invention provides the hydrophobic finish compositioncomprising;

-   -   (i) hydraulic component comprising fly ash, preferably the fly        ash comprises Class C fly ash, wherein the fly ash more        preferably comprises Class C fly ash in an amount from about 50%        to about 85% by weight of the finish composition on a water        inclusive basis;    -   (ii) film-forming polymer;    -   (iii) at least one silane compound selected from the group        consisting of:        -   (a) silane compounds having a molecular weight of at least            about 150,        -   (b) silane compounds having a general chemical formula (I):

(R¹O)_(m)—Si—X_(4-m)  (I)

-   -   -   wherein R¹O is an alkoxy group, X is an organofunctional            group, and m ranges from 1 to 3, and        -   (c) mixtures of silane compounds (a) and (b); and

    -   (iv) an extended flow time retention agent comprising at least        one member of the group consisting of carboxylic acids, salts of        carboxylic acids, and mixtures thereof.

Thus, the present invention more preferably provides a hydrophobicfinish composition comprising a hydraulic component which comprisesClass C fly ash, film-forming polymer, silane compound of the chemicalformula (I):

(R¹O)_(m)—Si—X_(4-m)  (I)

where R¹O is an alkoxy group, preferably C1-C12 alkoxy, X is anorganofunctional group, and m ranges from 1 to 3, and

an extended flow time retention agent comprising either one or morecarboxylic acids, salts of carboxylic acids, or mixtures thereof.

In another aspect, the invention provides a cementitious articlecomprising, consisting of, or consisting essentially ofcementitious-based layer, and the above described hydrophobic finishcomposition. The hydrophobic finish composition comprises a hydrauliccomponent which comprises:

-   -   (i) fly ash, preferably the fly ash comprises Class C fly ash,        wherein the fly ash more preferably comprises Class C fly ash in        an amount from about 50% to about 85% by weight of the finish        composition on a water inclusive basis;    -   (ii) film-forming polymer; and    -   (iii) an extended flow time retention agent comprising at least        one member of the group consisting of carboxylic acids, salts of        carboxylic acids, and mixtures thereof.

Preferably the hydrophobic finish composition comprises a hydrauliccomponent which comprises:

-   -   (i) fly ash, preferably the fly ash comprises Class C fly ash,        wherein the fly ash more preferably comprises Class C fly ash in        an amount from about 50% to about 85% by weight of the finish        composition on a water inclusive basis;    -   (ii) film-forming polymer;    -   (iii) at least one silane compound selected from the group        consisting of:        -   (a) silane compounds having a molecular weight of at least            about 150,        -   (b) silane compounds having a general chemical formula (I):

(R¹O)_(m)—Si—X_(4-m)  (I)

-   -   -   wherein R¹O is an alkoxy group, X is an organofunctional            group, and m ranges from 1 to 3, and        -   (c) mixtures of silane compounds (a) and (b); and

    -   (iv) an extended flow time retention agent comprising at least        one member of the group consisting of carboxylic acids, salts of        carboxylic acids, and mixtures thereof.

The hydrophobic finish composition faces an outer surface of the layerof the article. In some embodiments, the layer has two parts, with afinish on either side of the layer, to form a sandwich structure. Thelayer may be Portland cement based or gypsum based or any otherinorganic cement based material.

In another aspect, the invention provides a mat-faced cementitious boardcomprising, consisting of, or consisting essentially ofcementitious-based core, fibrous mat, and the above describedhydrophobic finish composition. The hydrophobic finish compositioncomprises a hydraulic component which comprises:

-   -   (i) fly ash, preferably the fly ash comprises Class C fly ash,        wherein the fly ash more preferably comprises Class C fly ash in        an amount from about 50% to about 85% by weight of the finish        composition on a water inclusive basis;    -   (ii) film-forming polymer; and    -   (iii) an extended flow time retention agent comprising at least        one member of the group consisting of carboxylic acids, salts of        carboxylic acids, and mixtures thereof.

Preferably the hydrophobic finish composition of the mat-facedcementitious board comprises a hydraulic component which comprises:

-   -   (i) fly ash, preferably the fly ash comprises Class C fly ash,        wherein the fly ash more preferably comprises Class C fly ash in        an amount from about 50% to about 85% by weight of the finish        composition on a water inclusive basis;    -   (ii) film-forming polymer;    -   (iii) at least one silane compound selected from the group        consisting of:        -   (a) silane compounds having a molecular weight of at least            about 150,        -   (b) silane compounds having a general chemical formula (I):

(R¹O)_(m)—Si—X_(4-m)  (I)

-   -   -   wherein R¹O is an alkoxy group, X is an organofunctional            group, and m ranges from 1 to 3, and        -   (c) mixtures of silane compounds (a) and (b); and

    -   (iv) an extended flow time retention agent comprising at least        one member of the group consisting of carboxylic acids, salts of        carboxylic acids, and mixtures thereof.

The hydrophobic finish composition faces an outer surface of the layer.In some embodiments, the layer has two parts, with a finish on eitherside of the layer, to form a sandwich structure. The cementitious-basedcore may be Portland cement based or gypsum based or any other inorganiccement based material. The fiber mat has an inner surface facing atleast one face of the cementitious-based core and an outer surfaceopposite the inner surface. The hydrophobic finish composition faces theouter surface of the mat, opposite the inner face that faces thecementitious-based core. The core is thicker than the finish. In someembodiments, the mat has two parts, with a mat on either side of thecementitious-based core, to form a sandwich structure. The termorganofunctional group as used in the present specification is asubstituted or unsubstituted organic (carbon-containing) moiety.

In another aspect, the invention provides a hydrophobic finishcomposition, cementitious article, and mat-faced cementitious boardwherein, rather than specifying the silane of the hydrophobic finishcomposition, cementitious article, and mat-faced cementitious board asbeing a silane compound of the above-listed of the chemical formula (I),the silane is specified as a silane compound having a molecular weightof at least about 150 Daltons (e.g., at least about 175, at least about200, or at least about 250).

Thus, for example, the present invention preferably provides ahydrophobic finish composition comprising a hydraulic component whichcomprises Class C fly ash, film-forming polymer, silane compounds havinga molecular weight of at least about 150, and an extended flow timeretention agent comprising one or more carboxylic acids, salts ofcarboxylic acids, or mixtures thereof.

Optionally the invention provides a hydrophobic finish composition,cementitious article, and mat-faced cementitious board wherein thissilane is a silane of above-listed chemical formula (I) having amolecular weight of at least about 150 Daltons (e.g., at least about175, at least about 200, or at least about 250).

The above described finish compositions can be applied in a wet state insome embodiments. The Class C fly ash is preferably present in an amountfrom about 50% to about 85% by weight of the wet finish composition. Inthe present specification, the term wet basis means a water inclusivebasis. In other words based on weight of the total composition includingwater. The water may be added externally and/or it may come from thepolymer dispersion when the polymer is added in a liquid form. Likewisethe term wet state or wet composition means including water. Incontrast, dry basis means a water free basis.

The hydrophobic finish composition preferably comprises the film-formingpolymer in an amount from about 5% to about 25% by weight of the wetfinish. The hydrophobic finish composition preferably comprises thealkyl alkoxysilane of chemical formula (I) and/or having a molecularweight of at least about 150 Daltons (e.g., at least about 175, at leastabout 200, or at least about 250) in an amount of about 5% or less byweight of the wet finish. The hydrophobic finish composition typicallycomprises the extended flow time retention agent, which is at least onemember of the group consisting of carboxylic acids, salts of carboxylicacid, and combinations thereof, in a total amount of 0.05 to 1.0 wt % ofbased upon dry (water free) weight of the hydraulic component.

Advantageously, hydrophobic finish coatings and products (e.g.,cementitious panels or articles) according to embodiments of theinvention exhibit one or more superior properties, such as waterpenetration resistance and/or impermeability; water durability anderosion resistance; bond with a variety of finishes, adhesives, andcementitious mortars; lower surface absorption resulting in significantreduction in usage of externally applied finishes and adhesives;aesthetics; and/or mold and mildew resistance.

In a preferred embodiment to improve water resistance and permit use ofrelatively less hydrophobic finish composition, the fibrous mat forsurface reinforcing the inorganic cementitious panel is pre-coated witha binder coating. This results in a mat-faced cementitious boardcomprising, consisting of, or consisting essentially of

-   -   the above described cementitious-based core,    -   the fibrous mat comprising a glass mat substrate having        non-woven glass fibers- and a binder coating comprising polymer        binder and inorganic filler, wherein the inorganic filer is        selected from at least one member of the group consisting of        inorganic pigment and inorganic binder, the binder coating is        present in an amount of about 40 lbs/MSF to about 165 lbs/MSF,        more preferably about 50 lbs/MSF to about 100 lbs/MSF, and most        preferably about 61 lbs/MSF to about 75 lbs/MSF, wherein the        binder coating uniformly penetrates the glass mat substrate from        one side of the coated glass mat to a depth which is a fraction        of the thickness of the coated glass mat, and    -   a layer of the above described hydrophobic finish composition,        wherein the above described hydrophobic finish composition        optionally comprises silane,    -   wherein the layer of the above described hydrophobic finish        composition adheres to the side of the fibrous mat coated with        the binder coating and the cementitious-based core adheres to        the opposed side of the fibrous mat.

The present specification uses the term “pre-coated non-woven glassfiber mat” for the mat of this embodiment having a binder coating ofabout 40 lbs/MSF to about 165 lbs/MSF, more preferably about 50 lbs/MSFto about 100 lbs/MSF, and most preferably about 61 lbs/MSF to about 75lbs/MSF, wherein the coating uniformly penetrates the glass matsubstrate from one side of the coated glass mat to a depth which is afraction of the thickness of the coated glass mat. Thus, in addition tothe at most small amount of substantially uniformly distributed polymerbinder which an uncoated mat has, a pre-coated mat has an additionalbinder coating of polymer binder and inorganic filler applied to oneside to penetrate at most partially through the thickness of the mat.Thus, a pre-coated non-woven glass fiber mat has one side coated withthe binder coating and the other side uncoated to expose a raw glassfiber side. The term “pre-coated” is employed in the presentspecification because the non-woven glass fiber mat is coated with thebinder coating before contacting the cementitious slurry that willbecome the core of the board.

In embodiments employing the pre-coated mat the hydrophobic finishcomposition layer is adhered to the coated surface of the coated fibrousmat rather than the raw glass fiber side. The cementitious-based core isadhered to the raw glass fiber side.

A pre-coated mat differs from an uncoated mat. For example, an acrylicpre-coated glass mat differs from an “uncoated” glass mat using acrylicbinder.

For purposes of the present specification an uncoated glass fiber mat isdefined as a glass fiber mat having an overall weight of 15-40 lbs/MSFand has at most a small amount of polymer binder substantially uniformlydistributed, for example 19-27 wt % of the overall mat is polymerbinder, but there is no inorganic filler. The thickness of an uncoatedglass mat is typically 20-40 mil.

Also, a pre-coated mat is heavier than the uncoated mat. A pre-coatedmat, in addition to the weight of the non-woven glass mat substrate,40-165 lbs./MSF (pounds per thousand square feet) of binder coating iscoated on one side of the non-woven glass mat substrate. The weight ofthe non-woven glass mat substrate prior to applying the binder coatingis 10-50 lbs./MSF. Thus, after applying the binder coating to make thepre-coated glass mat the weight of this pre-coated glass mat is 50-215lbs./MSF. Preferably the non-woven glass mat substrate before coatingweighs between about 12 and about 50 lbs./MSF, more preferably about14.5-26.5 lbs./MSF. Preferably 50-100 lbs./MSF, more preferably 61 to 75lbs./MSF, of binder coating is coated on one side of the non-woven glassmat substrate. On average, the weight of the coated glass mat per unitarea is no more than about six times the weight of the glass matsubstrate prior to coating. The coating preferably also imparts atensile strength to the coated glass mat which on average is at least1.33 times greater than the tensile strength of the glass mat substratewithout the coating.

The binder coating comprises binder polymer and inorganic filler. Thebinder coating is substantially uniformly distributed across the oneside of the mat. Thus, the binder coating only partially permeates intothe glass mat substrate. The other side exposes raw glass fibers coatedat most with a small amount of binder polymer and no inorganic filler.The binder coating uniformly penetrates the glass mat substrate to adesired fractional thickness of the coated glass mat. The penetration ofthe binder coating into the glass mat substrate extends a depth of from10% of a thickness of the coated glass mat to 75% of the thickness ofthe coated glass mat. Preferably the penetration of the binder coatinginto the glass mat substrate extends a depth of from 25% of a thicknessof the coated glass mat to 75% of the thickness of the coated glass mat.Moreover, a non-coated thickness of the coated glass mat is sufficientlythick for bonding purposes with, e.g., a gypsum slurry or othercementitious core materials. However, the non-coated thickness may havethe minor amount of polymer binder normally associated with anon-pre-coated fiber mat.

The fibers of the pre-coated non-woven mats are also bound together bythe binder coating. However, the porosity of the coated mat issufficiently low that it is not permeable to cementitious, for examplegypsum, slurry. However, when gypsum slurry is employed the porosity isalso sufficient to allow water vapor to escape from the gypsum slurrywhen heated. Thus, the coating provides the coated glass mat withporosity sufficient to allow water vapor to escape from the gypsumslurry when heated. Preferably, such porosity is in a range from about1.3 Cubic Feet per Minute (CFM) (all CFM data given are also “per squarefoot per”) to about 5.0 CFM. The coating is preferably a coating blendcomprised of water, latex binder, and inorganic binder.

The polymer binder used in the binder coating with inorganic filler canbe any polymer binder typically used in the mat industry. Suitablebinders include, without limitation, urea formaldehyde, melamineformaldehyde, stearated melamine formaldehyde, polyester, acrylics,polyvinyl acetate, urea formaldehyde or melamine formaldehyde modifiedor blended with polyvinyl acetate or acrylic, styrene acrylic polymers,and the like, as well as combinations thereof. Preferably the polymerbinder is a latex. Examples of polymer latex binders used with theinorganic filler are, but are not limited to: Styrene-Butadiene-Rubber(SBR), Styrene-Butadiene-Styrene (SBS), Ethylene-Vinyl-Chloride (EVCI),Poly-Vinylidene-Chloride (PVdC), modified Poly-Vinyl-Chloride (PVC),Poly-Vinyl-Alcohol (PVOH), Ethylene-Vinyl-Actate (EVA),Poly-Vinyl-Acetate (PVA), and Styrene-Acrylate (SA). Most preferably thepolymer binder is acrylic latex. No asphalt is used as a binder in thisinvention.

The inorganic filler of the binder coating is at least one of inorganicpigment and inorganic binder. An example of an inorganic pigment isgypsum (calcium sulfate dihydrate). Examples of the inorganic binderswhich are used with the latex binders in the coatings of this inventionare, but are not limited to the following: calcium oxide, calciumsilicate, calcium sulfate hemihydrate, magnesium oxychloride, magnesiumoxysulfate, and other complexes of some Group IIA elements (alkalineearth metals), as well as aluminum hydroxide. One example of such acomplex inorganic binder is Portland cement.

The invention provides for a hydrophobic finish composition, an articlecomprising the hydrophobic finish composition, and a mat faced boardcomprising the hydrophobic finish composition. Hydrophobic finishcompositions described as preferred are likewise preferred for thearticle comprising the hydrophobic finish composition, and the mat facedboard comprising the hydrophobic finish composition. Thus,silane-containing hydrophobic finish compositions are preferred for thearticle comprising the hydrophobic finish composition, and the mat facedboard comprising the hydrophobic finish composition. However, anotherpreferred embodiment is the mat faced board comprising the hydrophobicfinish composition wherein the mat is the pre-coated mat. In the matfaced board, comprising the hydrophobic finish composition wherein themat is the pre-coated mat, silane is preferred for improved waterresistance. However, the mat faced board, comprising the hydrophobicfinish composition wherein the mat is the pre-coated mat, having anabsence of silane in the hydrophobic finish composition is preferred forreduced cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic diagram of a composite board of thepresent invention.

FIG. 1A illustrates a schematic diagram of a composite underlayment ofthe present invention.

FIG. 2A is a schematic side view illustrating a roller assemblycomprising a finish roller with circumferential grooves defined thereinapplying a hydrophobic finish composition to a mat-faced cementitiousboard with the assembly in a direct finish orientation, in accordancewith embodiments of the invention.

FIG. 2B is a front schematic view of the roller assembly taken along theline 1B-1B depicted in FIG. 2A.

FIG. 3A is a schematic side view illustrating a roller assemblycomprising a finish roller with circumferential grooves defined thereinapplying a hydrophobic finish composition to a mat-faced cementitiousboard with the assembly in a reverse finish orientation, in accordancewith embodiments of the invention.

FIG. 3B is a front schematic view of the roller assembly taken alone theline 2B-2B depicted in FIG. 3A.

FIG. 4 shows a Sheen cup used in Example 1.

FIG. 5 shows a plot of Sheen cup flow time readings for threehydrophobic finish coating mixtures of Example 1.

FIG. 6 shows a plot of Sheen cup flow time readings for threehydrophobic finish coating mixtures of Example 2.

FIG. 7(a) shows temperature rise data for fly ash and water mixes ofExample 3.

FIG. 7(b) shows temperature rise data for fly ash and polymer mixes ofExample 3.

FIG. 8 shows temperature rise data for fly ash and water mixes ofExample 4.

FIG. 9 shows temperature rise data for fly ash and polymer mixes ofExample 4.

FIG. 10 shows Sheen Cup Flow Time (seconds) versus Coating Age (minutes)for Example 6.

FIG. 11 shows Sheen Cup Flow Time (seconds) versus Coating Age (minutes)data for Example 7.

FIG. 12 shows Sheen Cup Flow Time (seconds) versus Coating Age (minutes)for Example 8

FIG. 13 shows Sheen Cup Flow Time (seconds) versus Coating Age (minutes)of Example 9.

FIG. 14 illustrates a schematic diagram of a composite board 302 of thepresent invention employing a pre-coated glass mat.

FIG. 14A illustrates a schematic diagram of a coated board of thepresent invention.

FIG. 15 shows a pre-coated glass fiber mat.

FIG. 16 shows data for surface water absorption (Cobb) results forExample 11

FIG. 17 shows data for tile bond results for Example 11.

FIG. 18(a) shows optical images of glass mat, 20× uncoated for Example11.

FIG. 18(b) shows optical images of glass mat, 20× pre-coated for Example11

FIG. 19(a) shows the cross section of hand coated samples, 50× for 50lb/msf hydrophobic finish coating for Example 11.

FIG. 19(b) shows the cross section of hand coated samples, 50× for 100lb/msf hydrophobic finish coating for Example 11.

FIG. 20 shows data for surface water absorption (Cobb) results forExample 12.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a hydrophobic finish comprising,consisting of, or consisting essentially of fly ash, film-formingpolymer, preferably silane compound, and an extended flow time retentionagent comprising a member of the group consisting of carboxylic acids,salts of carboxylic acids, or mixtures thereof. Preferably the fly ashcomprises Class C fly ash, wherein the fly ash more preferably comprisesClass C fly ash in an amount from about 50% to about 85% by weight ofthe finish composition on a water inclusive basis.

The present invention is directed, at least in part, to improving waterresistance in cementitious product, such as mat-faced board. Productaccording to the invention comprises, consists of, or consistsessentially of cementitious core and the above-mentioned hydrophobicfinish facing an outer surface of the core. The hydrophobic finishcomprises, consists of, or consists essentially of fly ash, film-formingpolymer, and an extended flow time retention agent comprising a memberof the group consisting of carboxylic acids, salts of carboxylic acids,or mixtures thereof. Preferably the hydrophobic finish also comprises asilane. Preferably the fly ash comprises Class C fly ash, wherein thefly ash more preferably comprises Class C fly ash in an amount fromabout 50% to about 85% by weight of the finish composition on a waterinclusive basis.

In some embodiments, product is board that comprises, consists of, orconsists essentially of cementitious core (e.g., gypsum-based core),fibrous mat, and hydrophobic finish that faces an outer surface of themat, where the mat has an inner surface that can face a gypsum core, andthe outer surface is opposite the inner face. The term “faces,” as usedherein, means that other components may optionally be between the finishand mat, or between the mat and core, in accordance with embodiments ofthe invention (as defined herein). In some embodiments, the mat can bein at least two parts, with, for example, a mat on either side of thegypsum-based core to form a sandwich arrangement as known in the art. Inembodiments where the mat has more than one part, at least one mat, andin some embodiments all mats, have hydrophobic finish facing therespective outer surfaces of the mat(s).

Furthermore, product according to the invention achieves waterresistance and/or water barrier properties without compromising strengthor flexibility of the product. Thus, product of the invention does notbecome too rigid or brittle, but rather achieves desirable mechanicalproperties such as nail-pull resistance, flexural strength, corehardness, end and edge hardness, surface water absorption, and/orhumidified deflection in accordance with ASTM C1178 Coated Glass MatWater-Resistant Gypsum Backing Panel, ASTM C1177 Glass Mat GypsumSubstrate to use as Sheathing, and ASTM C1658 Glass Mat Gypsum PanelsSec. 7 Glass Mat Water-Resistant Gypsum Panel. In addition, the shearbond strength of the panels of the invention (e.g., when bonded usingset cement mortar or organic adhesive) exceeds about 50 psi when testedin accordance to the ASTM C1325 standard. This property is useful insome embodiments that can be used as substrates to bond ceramic tilesand stones using thin set cement mortars or organic adhesives.

Embodiments of the finish composition of the invention further exhibitsurprising flexibility. The flexible nature of the hydrophobic finishcomposition is particularly useful in some embodiments in resistingformation of cracks and mechanical deterioration due to various factorsduring the life cycle of the product and possibly the building orstructure containing the product. These factors include, for example,flexing of the panel during handling or installation; flexing anddeformation of the panel due to externally applied loads; scratching thepanel from construction equipment and tools such as mortar trowels,etc.; material shrinkage or expansion due to hygrothermal changes; watererosion; vapor pressure; and freezing and thawing environmental cycling.

Also, some embodiments of product of the invention achieve the desiredfeatures (e.g., anti-water penetration, water impermeability, strength,and/or flexibility) without requiring finish composition of substantialthickness and/or without requiring significant quantities of Class C flyash, silane, or film-forming polymer, as described herein, due to thesurprising and unexpected synergy of the ingredients in the finishcomposition.

Embodiments of board according to the present invention can be used in anumber of interior and exterior applications, particularly where waterresistance and especially waterproofness would be beneficial. Forexample, board in accordance with the invention can be used asbackerboard, such as might be useful in the installation of ceramictiles and natural stone in wet and dry areas of buildings or otherstructures. Non-limiting examples of tile backer applications wouldinclude wet areas of buildings or other structures, such as in kitchensand bathrooms, including shower stalls, backsplashes, countertops,floors, and the like.

Board according to embodiments of the invention can also be used forexterior weather barrier panels, such as for exterior sheathing. In thisrespect, the board can be used as an exterior sheathing panel to providean integrated weather barrier. In other embodiments, board according tothe invention can be used as a roof cover board having desirable waterdurability and low surface absorption properties for this application.Such low absorption may be useful to reduce usage of, for example,externally applied finishings and adhesives. In still other embodiments,board according to the invention can be used as exterior wallsubstrates. Such exterior wall substrates may be useful in a number ofways, such as for installation of a variety of component and finishmaterials, such as foam plastics, cementitious base finishes and thelike, in exterior insulation finish systems (EIFS), and direct-appliedexterior finish systems (DEFS), as known in the art. In one aspect, theboard is useful under exterior claddings. In other embodiments, boardaccording to the invention can be used as a poured, preferablyself-leveling, flooring composition, for example a floor underlayment,having the cementitious core and the hydrophobic finish facing the outersurface of the floor. In other embodiments, board according to theinvention can be used as an interior wall or ceiling where waterresistance is desired.

The following TABLE A lists typical and preferred compositions for thehydrophobic finish compositions of the present invention, and thesehydrophobic finish compositions provided as a component of acementitious article or cementitious board of the present invention. AnyTABLE A “more preferred” or “most preferred” range for one or morecomponents of the hydrophobic finish composition may be selected tomodify the “preferred” composition of the present invention. However,preferably the more preferred features are used together and preferablythe most preferred features are used together. All percentages in TABLEA, as well as the rest of this specification, are in weight percentunless otherwise indicated.

TABLE A Preferred More Preferred Most Preferred Hydraulic 50% to about85% by weight of the wet 55% to about 75% by weight of the wet 60% toabout 70% by weight of the wet component finish composition, wherein atleast finish composition, wherein at least finish composition, whereinat least half of the hydraulic component by half of the hydrauliccomponent by half of the hydraulic component by weight is Class C flyash* weight is Class C fly ash* weight is Class C fly ash* Film-formingabout 5% to about 25% by weight of about 7.5% to about 22.5% by weightof about 10% to about 20% by weight of polymer (solids basis) the wetfinish composition the wet finish composition the wet finish compositionSilane Compound 5% by weight or less of the wet 0.1-3% by weight of thewet finish 0.2-1% by weight of the wet finish finish compositioncomposition composition Extended flow time 0.05-1.00 wt. % by weight ofhydraulic 0.075-0.75 wt. % by weight of hydraulic 0.10-0.50 wt. % byweight of hydraulic retention agent component (on a dry basis)**component (on a dry basis)** component (on a dry basis)** comprising oneor more carboxylic acids, one or more salts of carboxylic acids, ormixtures thereof One or more 50% or less by weight of the wet 45% orless by weight of the wet 40% or less by weight of the wet optionalinorganic finish composition finish composition finish compositionfillers and aggregates Optional Water about 0% to about 5% by weight ofthe about 0% to about 3% by weight of the about 0% to about 1% by weightof the reducing admixture wet finish composition wet finish compositionwet finish composition additives Optional colorants about 0% to about 2%by weight of the about 0% to about 1.5% by weight of about 0% to about1% by weight of the wet finish composition the wet finish compositionwet finish composition Water 5 to 30% by weight of the wet 7.5 to 25% byweight of the wet 10 to 20% by weight of the wet finish compositionfinish composition finish composition *The term “wet finish composition”when used in this specification means the composition including water;the term “wet basis” when used in this specification means based on thecomposition including water. **The term “dry basis” when used in thisspecification means a water free basis.

As used in the present application percent means weight percent unlessotherwise indicated.

A. Hydraulic Component

The finish composition includes hydraulic component comprising fly ash,preferably the fly ash comprises Class C fly ash, wherein the fly ashmore preferably comprises Class C fly ash in an amount from about 50% toabout 85% by weight of the finish composition on a water inclusivebasis. In general the finish composition hydraulic component comprisesClass C fly ash or an equivalent fly ash. For purposes of the presentinvention a Class C fly ash is defined as a fly ash containing a limecontent of at least 10% by weight of the fly ash and a fly ash isconsidered equivalent to Class C fly ash if it contains sufficientlyhigh lime (CaO) content, wherein sufficient lime is at least about 10 wt%. Preferably the Class C fly ash or the equivalent fly ash has greaterthan about 20 wt %, and more preferably greater than 25 wt % of thetotal weight of fly ash, and most preferably about 25 to 45 wt % of thetotal weight of fly ash.

The hydraulic component preferably comprises, consists of, or consistsessentially of the Class C fly ash. Class C type of fly ash is a highlime content fly ash that can be obtained, e.g., from processing ofcertain coals. For example, in some embodiments, the Class C fly ash hasa lime content of at least about 10%, such as at least about 12%, atleast about 15%, at least about 18% or at least about 20% by weight ofthe fly ash. ASTM C-618 describes the characteristics of Class C fly ash(e.g., Bayou Ash Inc., Big Cajun, II, LA or Boral Material Technologies,Scherer Plant—Juliette, Ga.). The Class C fly ash can have lime contentas high as about 45%.

When mixed with water, the fly ash sets similarly to a cement or gypsum.In some embodiments, the finish composition comprises Class C fly ashand is substantially free of any other hydraulic material. As usedherein, “substantially free” of such other hydraulic material means thatthe composition contains 0 wt. % based on the weight of the composition,or no such other hydraulic material, or an ineffective or immaterialamount of such other hydraulic material. An example of an ineffectiveamount is an amount below the threshold amount to achieve the intendedpurpose of using such setting material, as one of ordinary skill in theart will appreciate. An immaterial amount may be, e.g., about 10% orless, about 5% or less, about 2% or less, about 1% or less, about 0.5%or less, or about 0.1% or less, based on the weight of the composition,depending on the ingredient, as one of ordinary skill in the art willappreciate. As mentioned in the TABLE A above—at least half of thehydraulic component by weight is Class C fly ash.

TABLE B shows the oxide composition (XRF analysis) of the Class C flyash used in the examples of this invention. This fly ash is from theScherer Power Plant, Juliette, Ga. and is supplied by Boral MaterialTechnologies, Inc.

TABLE B Oxide Wt % CaO 27.36 SO₃ 2.08 MgO 5.70 Na₂O 1.47 Al₂O₃ 18.18Fe₂O₃ 5.64 SiO₂ 33.24 P₂O₅ 1.54 K₂O 0.36 TiO₂ 1.33 LOI (110-750° C.)0.17

However, in other embodiments, use of other hydraulic components incombination with fly ash are contemplated, including cements, includinghigh alumina cements, calcium sulfates, including calcium sulfateanhydrite, calcium sulfate hemihydrates or calcium sulfate dihydrate,other hydraulic components and combinations thereof. Mixtures of flyashes are also contemplated for use, for example, mixtures of Class Cfly ash and Class F fly ash having at least 85% Class C fly ash. Silicafume (e.g., SKW Silicium Becancour, St. Laurent, Quebec, Canada) isanother preferred material.

Silica fume may be used in combination with fly ash. Silica fume, alsoknown as microsilica, (CAS number 69012-64-2, EINECS number 273-761-1)is an amorphous (non-crystalline) polymorph of silicon dioxide, silica.It is an ultrafine powder collected as a by-product of the silicon andferrosilicon alloy production and consists of spherical particles withan average particle diameter of 150 nm. The main field of application isas pozzolanic material for high performance concrete. It is sometimesconfused with fumed silica (also known as pyrogenic silica, CAS number112945-52-5). However, the production process, particle characteristicsand fields of application of fumed silica are all different from thoseof silica fume.

When Portland cement, quick lime (CaO) or hydrated lime (Ca(OH)2) areincluded in the hydraulic component, they may produce heat and impactrheology such that the finish composition may be adversely affected suchas in the form of cracking or other damage. Accordingly, in someembodiments, Portland cement is included in the hydraulic component inan amount of about 50% or less by weight of the hydraulic component,such as about 45% or less, about 40% or less, about 35% or less, about30% or less, about 25% or less, about 20% or less, about 15% or less,about 10% or less, about 5% or less, about 1% or less, or about 0.1% orless. In the case of quick lime, if included, in some embodiments, it isincluded in an amount of about 10% or less by weight of the hydrauliccomponent, such as about 8% or less, about 5% or less, about 3% or less,about 1% or less, about 0.5% or less, or about 0.1% or less. Withrespect to hydrated lime, if included, in some embodiments, it isincluded in an amount of about 25% or less by weight of the hydrauliccomponent, such as about 20% or less, about 15% or less, about 10% orless, about 5% or less, about 1% or less, about 0.5% or less, or about0.1% or less.

Another reason Class C fly ash is desired is the increased life cycleexpectancy and increase in durability associated with its use. Duringthe hydration process, fly ash chemically reacts with the calciumhydroxide forming calcium silicate hydrates and calcium aluminatehydrates, which reduces the risk of leaching calcium hydroxide, makingthe composition less permeable. Class C fly ash also improves thepermeability of hydraulic compositions by lowering the water-to-cementratio, which reduces the volume of capillary pores remaining in the setcomposition. The spherical shape of fly ash improves the consolidationof the composition, which also reduces permeability. It is alsotheorized tricalcium aluminate, frequently present in fly ash, acts as aset accelerator to speed up the setting reactions. Calcium aluminate isusually found in fly ash, and it can lead to fast setting action. Thepresent invention provides the benefit of including the extended flowcontrol agent to facilitate industrial continuous production in spite ofthe presence of fast setting materials such as calcium aluminates in thehydraulic component.

In some embodiments, the fly ash has a mean particle size from about 1micron to about 100 microns. In embodiments of the invention, the meanparticle size of the fly ash can be, for example, as listed in TABLE 1below. In the table, an “X” represents the range “from about[corresponding value in first row] to about [corresponding value infirst column].” The indicated values represent mean particle size inmicrons. For ease of presentation, it will be understood each valuerepresents “about” that value. For example, the first “X” is the range“from about 1 micron to about 10 microns.”

TABLE 1 mean particle size of fly ash (microns) 1 10 20 30 40 50 60 7080 90 10 X 20 X X 30 X X X 40 X X X X 50 X X X X X 60 X X X X X X 70 X XX X X X X 80 X X X X X X X X 90 X X X X X X X X X 100 X X X X X X X X XX

Thus, the mean particle size can have a range between and including anyof the aforementioned endpoints.

In some embodiments, the hydraulic component is substantially free ofsilica (SiO₂), alumina (Al₂O₃) or iron oxide (Fe₂O₃). As used herein,“substantially free” of silica, alumina or iron oxide means that thecomposition contains 0 wt. % based on the weight of the composition, orno silica, alumina or iron oxide, or an ineffective or immaterial amountof silica, alumina or iron oxide. An example of an ineffective amount isan amount below the threshold amount to achieve the intended purpose ofusing such setting material, as one of ordinary skill in the art willappreciate. An immaterial amount may be, e.g., about 5% or less, about2% or less, about 1% or less, or about 0.1% or less, based on the weightof the composition, depending on the ingredient, as one of ordinaryskill in the art will appreciate.

However, if desired in some embodiments, silica, alumina, and/or ironoxide can be included. If included, in some embodiments, these materialsin total account for less than about 50% by weight of the hydrauliccomponent, such as for example, less than about 40%, less than about30%, less than about 20%, or less than about 10% by weight of thehydraulic component.

The amount of the hydraulic component (e.g., Class C fly ash alone or insome combination with other hydraulic material) in some embodiments canbe from about 50% to about 85% by weight of the wet finish composition.In embodiments of the invention, the amount of the hydraulic componentcan be, for example, as listed in TABLE 2 below. In the table, an “X”represents the range “from about [corresponding value in first row] toabout [corresponding value in first column].” The indicated valuesrepresent percentage by weight of the wet finish composition. For easeof presentation, it will be understood each value represents “about”that value. For example, the first “X” is the range “from about 50% byweight of the wet finish composition to about 55% by weight of thecomposition.” Wet finish composition means the total compositionincluding water before the water evaporation (the water can come fromvarious sources, for example a latex emulsion of polymer when added maybe 50% water and 50% polymer solids).

TABLE 2 (wt. %) 50 55 60 65 70 75 80 55 X 60 X X 65 X X X 70 X X X X 75X X X X X 80 X X X X X X 85 X X X X X X X

Thus, the amount of the hydraulic component, preferably Class C fly ash,can have a range between and including any of the aforementionedendpoints.

Preferably, the hydraulic component comprising Class C fly ash is in anamount from about 50% to about 85% by weight of the wet finish.

B. Film Forming Polymers

Film-forming polymer is included in embodiments of the finishcomposition. The film-forming polymer is preferably made from a pureacrylic, a rubber, a styrene butadiene rubber, a styrene acrylic, avinyl acrylic, or an acrylated ethylene vinyl acetate copolymer.Preferably film-forming polymer is derived from at least one acrylicmonomer selected from the group consisting of acrylic acid, acrylic acidesters, methacrylic acid, and methacrylic acid esters. For example, themonomers preferably employed in emulsion polymerization include methylacrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butylacrylate, butyl methacrylate, propyl acrylate, propyl methylacrylate,2-ethyl hexyl acrylate and methacrylate, cyclohexyl acrylate andmethacrylate, decyl-acrylate and methacrylate, isodecylacrylate andmethacrylate, benzyl acrylate and methacrylate, other acrylates,methacrylates and their blends, acrylic acid, methacrylic acid, styrene,vinyl toluene, vinyl acetate, vinyl esters of higher carboxylic acidsthan acetic acid, for example, vinyl versatate, acrylonitrile,acrylamide, butadiene, ethylene, vinyl chloride and the like, andmixtures thereof.

In some embodiments, the film-forming polymer comprises one or more ofthe following: acrylic polymers and copolymers, rubber-based polymersand copolymers such as styrene-butadiene rubber, copolymers of styreneand acrylic, copolymers of vinyl acetate and ethylene, copolymers ofvinyl chloride and ethylene, copolymers of vinyl acetate and VeoVa(vinyl ester of versatic acid), copolymers of vinyl laurate andethylene, terpolymers of vinyl acetate, ethylene andmethylmethaacrylate, terpolymers of vinyl acetate, ethylene and vinyllaurate, terpolymers of vinyl acetate, ethylene and VeoVa (vinyl esterof versatic acid), and any combination thereof.

In some embodiments, the film-forming polymer is water-soluble such as,for example, a latex polymer. The polymer can be used in either liquidform or as a re-dispersible polymer. One example is a copolymer ofmethyl methacrylate and butyl acrylate (e.g., FORTON VF 774, EPS Inc.,Marengo, Ill.).

Preferably, the film-forming polymer comprises one or more of thefollowing: acrylic polymers and copolymers, rubber-based polymers andcopolymers such as styrene-butadiene rubber, copolymers of styrene andacrylic, copolymers of vinyl acetate and ethylene, copolymers of vinylchloride and ethylene, copolymers of vinyl acetate and VeoVa vinyl esterof versatic acid (commercially available under the mark VeoVa from ShellChemical Company), copolymers of vinyl laurate and ethylene, terpolymersof vinyl acetate, ethylene and methyl methacrylate, terpolymers of vinylacetate, ethylene and vinyl laurate, terpolymers of vinyl acetate,ethylene, and vinyl esters of branched tertiary monocarboxylic acids(e.g. vinyl ester of versatic acid commercially available under the markVeoVa from Shell Chemical Company or sold as EXXAR neo vinyl esters byExxonMobil Chemical Company), itaconic acid, crotonic acid, maleic acid,fumaric acid, and ethylene, and any combination thereof.

As used herein, “molecular weight” in reference to a polymer or anyportion thereof, means to the weight-average molecular weight (“M_(w)”)of the polymer or portion. In one embodiment, the polymers for use inthe present invention exhibit a weight average molecular weight ofgreater than or equal to 10,000 grams per mole (“g/mole”). For example,in a range of 30,000 to 5,000,000 g/mole. More typically the polymer ofthe present invention exhibits a weight average molecular weight of fromabout 100,000 g/mole to about 2,500,000 g/mole, or more typically about150,000 g/mole to about 1,000,000 g/mole.

Commonly used monomers are butyl acrylate, methyl methacrylate, ethylacrylate and the like. Preferably, the monomers include one or moremonomers selected from the group consisting of n-butyl acrylate, methylmethacrylate, styrene, and 2-ethylhexyl acrylate.

The at least one polymer is preferably derived from at least one acrylicmonomer selected from the group consisting of acrylic acid, acrylic acidesters, methacrylic acid, and methacrylic acid esters. For example, theat least one film-forming polymer can be a butyl acrylate/methylmethacrylate copolymer or a 2-ethylhexyl acrylate/methyl methacrylatecopolymer. For example, the at least one polymer can be a butylacrylate/methyl methacrylate copolymer or a 2-ethylhexyl acrylate/methylmethacrylate copolymer. Typically, the at least one polymer is furtherderived from one or more monomers selected from the group consisting ofstyrene, alpha-methyl styrene, vinyl chloride, acrylonitrile,methacrylonitrile, ureido methacrylate, vinyl acetate, vinyl esters ofbranched tertiary monocarboxylic acids, itaconic acid, crotonic acid,maleic acid, fumaric acid, ethylene, and C4-C8 conjugated dienes such as1,3-butadiene, isoprene or chloroprene.

For example, the at least one film-forming polymer can be a pureacrylic, a styrene acrylic, a vinyl acrylic or an acrylated ethylenevinyl acetate copolymer.

The pure acrylics preferably comprise acrylic acid, methacrylic acid, anacrylate ester, and/or a methacrylate ester as the main monomers). Thestyrene acrylics preferably comprise styrene and acrylic acid,methacrylic acid, an acrylate ester, and/or a methacrylate ester as themain monomers. The vinyl acrylics preferably comprise vinyl acetate andacrylic acid, methacrylic acid, an acrylate ester, and/or a methacrylateester as the main monomers. The acrylated ethylene vinyl acetatecopolymers preferably comprise ethylene, vinyl acetate and acrylic acid,methacrylic acid, an acrylate ester, and/or a methacrylate ester as themain monomers. The monomers can also include other main monomers such asacrylamide and acrylonitrile, and one or more functional monomers suchas itaconic acid and ureido methacrylate, as would be readily understoodby those skilled in the art. In a particularly preferred embodiment, thefilm-forming polymer is a pure acrylic such as a butyl acrylate/methylmethacrylate copolymer derived from monomers including butyl acrylateand methyl methacrylate.

A typical film-forming polymer is comprised of one or more esters ofacrylic or methacrylic acid, typically a mixture, e.g. about 50/50 byweight, of a high T_(g) monomer (e.g. methyl methacrylate) and a lowT_(g) monomer (e.g. butyl acrylate), with small proportions, e.g. about0.5% to about 2% by weight, of acrylic or methacrylic acid. Thevinyl-acrylic polymers for example include vinyl acetate and butylacrylate and/or 2-ethyl hexyl acrylate and/or vinyl versatate. In atypical vinyl-acrylic polymer, at least 50% of the polymer formed iscomprised of vinyl acetate, with the remainder being selected from theesters of acrylic or methacrylic acid. The styrene/acrylic polymers aretypically similar to the acrylic polymers, with styrene substituted forall or a portion of the methacrylate monomer thereof.

The film-forming polymer (solid basis) can be present in someembodiments in an amount from about 5% to about 25% by weight of the wetfinish composition. In embodiments of the invention, the amount of thefilm-forming polymer can be, e.g., as listed in TABLE 3 below. In thetable, an “X” represents the range “from about [corresponding value infirst row] to about [corresponding value in first column].” Theindicated values represent percentage by weight of the wet finishcomposition. For ease of presentation, it will be understood that eachvalue represents “about” that value. For example, the first “X” is therange “from about 5% by weight of the wet finish composition to about 8%by weight of the wet finish composition.”

TABLE 3 (wt. %) 5 8 10 12 15 18 20 22 8 X 10 X X 12 X X X 15 X X X X 18X X X X X 20 X X X X X X 22 X X X X X X X 25 X X X X X X X X

Thus, the amount of the film-forming polymer can have a range betweenand including any of the aforementioned endpoints.

C. Silane Compound

Silane compound is preferably included in the finish composition inaccordance with the present invention. In some embodiments, the silaneis preferably within the general chemical formula (I):

(R¹O)_(m)—Si—X_(4-m)  (I)

where R¹O is an alkoxy group, X is an organofunctional group, and mranges from 1 to 3. With respect to the RO alkoxy group, in someembodiments, typically RO is a C1-C8 alkoxy, for example R can bemethoxy or ethoxy, although other alkoxy groups are contemplated and canbe included. The X organofunctional group can be any such hydrophobicityproviding group, such as C1-C12 alkyl, for example, methyl, ethyl,propyl, butyl, pentyl, hexyl or octyl. Long-chain organofunctionalgroups such as butyl, pentyl, hexyl and octyl groups are preferablyselected in some embodiments of the invention for their beneficial rolein providing enhanced hydrophobicity. Typically, the silane compound(e.g., alkyl alkoxysilane) has a molecular weight of at least about 150Daltons.

Preferably, the silane compound is one or more of octyltriethoxy silane,isooctyltriethoxy silane, octyltrimethoxy silane, isooctyltrimethoxysilane, butyltriethoxy silane, isobutyltriethoxy silane, butyltrimethoxysilane, or isobutyltrimethoxy silane.

While not being bound by any theory, it is believed silane compoundswith long-chain organofunctional groups X, for example butyl, pentyl,hexyl and octyl groups, are relatively more stable in the finishcomposition of embodiments of the present invention and thereforeprovide superior water repellency characteristics. Silanes crosslink orbond to inorganic surfaces through elimination of the alkoxy groupsafter hydrolysis and condensation reaction. The alkoxy groups react withthemselves and any hydroxy (OH) groups within the substrate whenmoisture is present, forming a silicone resin network. This formation ofstrong chemical bonds provides long term durability such as might becharacteristics of silicone treatments. However, in some embodiments,although generally less preferred, and excluded in some embodiments, itmay be possible to utilize small-chain organofunctional groups such asmethyl although their use may lead to less desirable hydrophobicity andanti-water penetration properties.

In some embodiments, silane compound (e.g., alkyl alkoxysilane)according to the invention is characterized by a molecular weight of atleast about 150, preferably at least about 175, at least about 200, atleast about 225, or greater. The silane compound can be added to themixture either in a concentrated form or in the form of an emulsion, asone of ordinary skill in the art will readily appreciate.

Some examples of suitable alkyl alkoxysilane compounds in accordancewith embodiments of the invention include, for example, octyltriethoxysilane, isooctyltriethoxy silane, octyltrimethoxy silane,isooctyltrimethoxy silane, butyltriethoxy silane, isobutyltriethoxysilane, butyltrimethoxy silane, or isobutyltrimethoxy silane, or anycombination thereof. In some embodiments, mixtures of silanes andsiloxane compounds can be utilized to provide the desired degree ofwater penetration resistance to the panels of the invention.

Silane compound can be present in accordance with embodiments of theinvention in an amount of about 5% by weight or less of the wet finishcomposition (total composition including its water). Preferably, thesilane compound is in an amount from about 0.1% to about 5% by weight ofthe wet finish composition.

In embodiments of the invention, the amount of the silane compound canbe, e.g., as listed in TABLE 4 below. In the table, an “X” representsthe range “from about [corresponding value in first row] to about[corresponding value in first column].” The indicated values representpercentage by weight of the wet finish composition. For ease ofpresentation, it will be understood each value represents “about” thatvalue. For example, the first “X” is the range “from about 0.1% byweight of the wet finish composition to about 0.5% by weight of the wetfinish composition.”

TABLE 4 0.1 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0.5 X 1 X X 1.5 X X X 2 X X X X2.5 X X X X X 3 X X X X X X 3.5 X X X X X X X 4 X X X X X X X X 4.5 X XX X X X X X X 5 X X X X X X X X X

Thus, the amount of silane compound can have a range between andincluding any of the aforementioned endpoints.

D. Extended Flow Time Retention Agent

The hydrophobic finish composition of the invention (also known as acoating composition) comprises an extended flow time retention agentcomprising, consisting, or consisting essentially of at least one memberof the group consisting of carboxylic acids, salts of carboxylic acids,or mixtures thereof. Preferably the salts are alkali (for example sodiumor potassium), alkaline (for example calcium), or ammonium salts, mostpreferably the salts are sodium or potassium salts. The hydrophobicfinish (coating) compositions of the invention comprising an extendedflow time retention agent stay fluid and workable for at least 30minutes or longer, preferably at least 60 minutes or longer, morepreferably at least 120 minutes or longer, and most preferably at least240 minutes or longer without stiffening.

Typically carboxylic acid has the chemical formula (II):

-   -   wherein R is an organofunctional group, the organic moiety may        be substituted or unsubstituted, for example it may be        substituted with one or more additional carboxyl functional        groups (—COOH);    -   wherein the salts of carboxylic acid have the chemical formula        (III)

-   -   wherein R is as defined in formula (II) and X⁺ is a cation, for        example sodium or potassium.

The term organofunctional group in the present specification means asubstituted or unsubstituted organic moiety.

Various carboxylic acid families particularly useful as extended flowtime retention agent in the compositions of this invention includetricarboxylic acids such as citric acid and isocitric acid; dicarboxylicacids such as malic acid, succinic acid and aldaric acids; sugar acidssuch as aldonic acids, uronic acids and aldaric acids; aromaticcarboxylic acids such as benzoic acid and salicylic acid; aromatic alphahydroxy acid such as mandelic acid; amino carboxylic acids such asethylene diamine tetra acetic acid (EDTA), ethylene glycol tetra aceticacid (EGTA), diethylene triamine penta acetic acid (DTPA) and ethylenediamine disuccinic acid (EDDS); alpha hydroxy acids such as tartaricacid; beta hydroxy acids such as salicylic acid. Typical aldonic acidsare gluconic acid, glyceric acid, and xylonic acid. Typical aldaricacids are tartaric acid, mucic acid, and saccharic acid. Typical uronicacids are glucuronic acid, galacturonic acid. These carboxylic acidfamilies, and alkali, alkaline, and ammonium salts thereof, mostpreferably sodium salts thereof and potassium salts thereof, areparticularly useful in the present invention.

A tricarboxylic acid is an organic carboxylic acid whose chemicalstructure contains three carboxyl functional groups (—COOH). The generalmolecular formula for dicarboxylic acids can be written as R—(CO₂H)₃,where R can be aliphatic or aromatic, preferably C3-C6 aliphatic, mostpreferably C3 aliphatic.

A dicarboxylic acid is an organic carboxylic acid whose chemicalstructure contains two carboxyl functional groups (—COOH). The generalmolecular formula for dicarboxylic acids can be written as HO₂C—R—CO₂H,where R can be a bond, aliphatic, or aromatic, preferably C1-C15aliphatic.

Sugar acids are monosaccharides with a carboxyl functional groups(—COOH). Preferred classes of sugar acids include Aldonic acids, Uronicacids, or Aldaric acids.

Aldonic acids are any of a family of sugar acids obtained by oxidationof the aldehyde functional group of an aldose to form a carboxylic acidfunctional group. Typical aldonic acids are glyceric acid, xylonic acid,gluconic acid, and ascorbic acid. Structural formula (IIa) shows thechemical structure of D-gluconic acid, an aldonic acid derived fromglucose:

Uronic acids are any of a family of sugar acids in which the terminalhydroxyl group of an aldose or ketose is oxidized. The Uronic acids haveboth carbonyl and carboxylic acid functional groups. They are sugars inwhich the terminal carbon's hydroxyl group has been oxidized to acarboxylic acid. Typical Uronic acids are Glucuronic acid, Galactouronicacid, and Iduronic acid. Structural formula (IIb) shows the chemicalstructure of beta-D glucuronic acid:

Aldaric acids are any of a family of sugar acids in which both ends ofan aldose are oxidized. An aldaric acid is an aldose in which both thehydroxyl function of the terminal carbon and the aldehyde function ofthe first carbon have been fully oxidized to carboxylic acid functions.(Oxidation of just the aldehyde yields an aldonic acid while oxidationof just the terminal hydroxyl group yields an uronic acid.) TypicalAldaric acids are Tartaric acid, meso-Galactaric acid, and D-Glucaricacid. Structural formula (IIc) shows the chemical formula of glucaricacid, also known as saccharic acid:

Aromatic carboxylic acids include compounds that contain a carboxylfunctional groups (—COOH) bonded to an aromatic ring.

Amino carboxylic acids have both the amine and the carboxylic acidgroups. Typical amino carboxylic acids have both the amine and thecarboxylic acid groups attached to the first (alpha-) carbon atom. Theyare known as 2-, alpha-, or α-amino acids (generic formula H₂NCHRCOOH,wherein R is a substituted or unsubstituted organic moiety). Aminocarboxylic acids can have multiple amino and/or multiple carboxylic acidgroups.

α-Hydroxy acids, or alpha hydroxy acids (ANAs), are a class of chemicalcompounds that contains a carboxylic acid substituted with a hydroxylgroup on the adjacent carbon. Tartaric acid and citric acid are examplesof alpha hydroxy acid. Glyceric acid, glycolic acid, and lactic acid arealso examples of alpha hydroxy acids. An alpha hydroxy acid contains acarboxylic acid functional group and hydroxy functional group separatedby one carbon atom. In contrast, a beta hydroxy acid or β-hydroxy acid(BHA) is an organic compound that contains a carboxylic acid functionalgroup and hydroxy functional group separated by two carbon atoms.Salicyclic acid is an example of beta hydroxy acid.

Preferably the extended flow time retention agents of the presentinvention are carboxylic acids selected from at least member of thegroup consisting of dicarboxylic acids, tricarboxylic acids, alphahydroxy acids, and sugar acids, and alkali, alkaline, or ammonium saltsthereof. Preferably the carboxylic acid salts of the present inventionare sodium or potassium salts.

Preferably for the finish compositions, articles, and mat facedcementitious boards of the present invention the extended flow timeretention agent comprises at least one member of the group consisting oftartaric acid, gluconic acid, citric acid, sodium gluconate, potassiumgluconate, potassium tartrate, sodium tartrate, potassium sodiumtartrate, sodium citrate, and potassium citrate. Preferred forms ofpotassium tartrate useful in this invention are also variously known asL(+)-potassium L-tartrate monobasic, tartaric acid monopotassium salt,potassium hydrogen L-tartrate, potassium hydrogen tartrate.

Examples of particularly preferred carboxylic acid based flow timeretention agents of this invention include citric acid, tartaric acid,and gluconic acid. Examples of more preferred flow time retention agentsof this invention include gluconic acid and tartaric acid. Tartaric acidis one of the most preferred flow time retention agents of thisinvention. Different forms of tartaric acids can be employed in thepresent invention including levotartaric acid, dextrotartaric acid,racemic acid and mesotartaric acid.

Examples of preferred flow time retention agents that are salts ofcarboxylic acids include sodium citrate, potassium citrate, sodiumgluconate, potassium gluconate, potassium tartrate, sodium tartrate,potassium sodium tartrate. Sodium gluconate, potassium gluconate,potassium tartrate, sodium tartrate, potassium sodium tartrate representsome of the more preferred flow time retention agents of this invention.Potassium tartrate is one of the most preferred flow time retentionagents of this invention; however, as described previously, tartaricacid is more preferred than potassium tartrate in the present invention.

According to this invention, the flow time retention agents based oncarboxylic acids are superior to their counterparts based on salts ofthe same carboxylic acid, particularly sodium and potassium salts. Forinstance, according to this invention, tartaric acid has been found tobe superior to potassium tartrate or sodium tartrate; alternatively,gluconic acid has been found to be superior to sodium gluconate orpotassium gluconate. Surprisingly it has also been discovered that thecoating compositions of this invention comprising carboxylic acid basedflow time retention agents provide significantly reduced surface waterabsorption than the corresponding compositions comprising salts of thesame carboxylic acid. This is an important discovery since a main use ofthe hydrophobic coatings of the present invention is for waterproofingapplications.

The compositions of the present invention may comprise carboxylic acidflow retention agents separately from the salts of carboxylic acid flowretention agent as shown, for example, in a number of the examples ofthe present specification. In the alternative, the compositions of thepresent invention may comprise carboxylic acid extended flow retentionagents together with the salts of carboxylic acid extended flowretention agent as shown, for example, in a number of other examples ofthe present specification.

Thus, the hydrophobic finish compositions of the invention can alsoutilize mixtures of carboxylic acids and salts of carboxylic acids asflow time retention agent. For instance, tartaric acid may be used incombination with potassium tartrate; or, tartaric acid may be used incombination with sodium gluconate; or gluconic acid may be used incombination with potassium tartrate; etc.

The carboxylic acid and/or carboxylate salt based flow time retentionagent can be present in accordance with embodiments of the invention inan amount from about 0.05% to about 1.00% by weight based upon weight ofthe hydraulic component on a water free (dry) basis. Thus, for exampleif there are 100 grams of hydraulic component solids with no water andthe carboxylic acid is 0.5% by weight based upon weight of the hydrauliccomponent, then there are 0.5 grams of carboxylic acid and the totalweight of the hydraulic component solids and the flow time retentionagent is 100.5 grams. Likewise for example, if there are 100 grams ofhydraulic component and the carboxylic acid is 0.50 wt % and the salt ofcarboxylic acid is 0.25 wt %, respectively, by weight based upon weightof the hydraulic component, then there are 0.50 grams of carboxylic acidand 0.25 grams of salt of carboxylic acid in the composition and thetotal weight of the hydraulic component solids and the flow timeretention agent is 100.75 grams.

In embodiments of the invention, the amount of the carboxylic acidand/or carboxylate salt can be, e.g., as listed in TABLE 5 below. InTABLE 5, an “X” represents the range “from about [corresponding value infirst row] to about [corresponding value in first column].” Theindicated values represent percentage by weight of the hydrauliccomponent. For ease of presentation, it will be understood each valuerepresents “about” that value. For example, the first “X” is the range“from about 0.05% by weight to about 1.00% by weight of the hydrauliccomponent.” A more preferred dosage of carboxylic acid and/orcarboxylate salt based flow time retention agent dosage is about 0.1% byweight to about 0.75% by weight of the hydraulic component. The mostpreferred dosage of carboxylic acid and/or carboxylate salt based flowtime retention agent is about 0.15% by weight to about 0.50% by weightof the hydraulic component.

TABLE 5 0.1 0.1 0.2 0.5 0.8 1 0.05 X 0.1 X X 0.2 X X X 0.5 X X X X 0.8 XX X X X 1 X X X X X X

Thus, the total amount of carboxylic acid and/or salt can have a rangebetween and including any of the aforementioned endpoints.

The extended flow time retention agents of the present invention areparticularly beneficial when operational conditions and parameters of agiven manufacturing process provide wet hydrophobic coating mixtureshaving high temperatures of up to 150° F. In absence of the extendedflow time retention agents of the present invention, the hightemperature of the wet hydrophobic coating mixtures is responsible forrapid material gelation and premature loss in material flow andprocessing properties. The addition of extended flow time retentionagents of the present invention to the hydrophobic coating compositionsof the invention allows the high temperature coatings to retain theirflow and processing properties for an extended duration thus making themanufacturing processes commercially viable.

Advantageously, during manufacture of the cementitious articles of thepresent invention, the coating composition stays fluid and workable forat least 30 minutes or longer, preferably at least 60 minutes or longer,more preferably at least 120 minutes or longer, and most preferably atleast 240 minutes or longer without stiffening.

The hydrophobic finish composition of this invention stays fluid andworkable at a particular hydrophobic finish coating temperature for atime of at least 30 minutes, preferably at least 60 minutes, morepreferably at least 120 minutes, and most preferably at least 240minutes. The particular hydrophobic finish coating temperature being atleast one of the following listed coating temperatures: about 70° F.,preferably about 90° F., more preferably about 110° F., still morepreferably about 130° F., and most preferably about 150° F.

A typical family of carboxylic acids for the present invention includesthose wherein R In above-listed chemical formula (II) is a C1-C20 alkylor C1-C12 alkyl. However, preferably the carboxylic acids and/or saltsof carboxylic acids used as extended flow time retention agents in thepresent invention are other than saturated carboxylic acids of formulaRCOOM wherein R is H or C1 to C20 alkyl or C1-C12 alkyl, and M is H, andsalts thereof. The saturated carboxylic acids of formula RCOOM and/orsalts thereof are optional, and typically not included in compositionsof the present invention.

The present carboxylic acids and/or salts of carboxylic acids differfrom polycarboxylates, sulfonated melamines, and sulfonated naphthalenesdisclosed as superplasticizers in US 20140272402 to Dubey et al,Cementitious Article Comprising Hydrophobic Finish. For example, theydiffer from superplasticizers such as ADVA CAST and ADVA CAST 500polycarboxylate ether superplasticizers by Grace Construction Products,Cambridge, Mass., SIKA VISCOCRETE G2 polycarboxylate ethersuperplasticizer from SIKA Corporation, Lyndhurst, N.J., ETHACRYL M andETHACRYL G polycarboxylate ether superplasticzer from available fromCoatex-Arkema, Genay, France, MELFLUX PCE239, MELFLUX PCE 541polycarboxlate ether superplasticizer from BASF, Trostberg, Germany, andDILOFLO GW Superplasticizer of Geo Specialty Chemicals, Cedartown, Ga.which is a sodium salt of sulfonated naphthalenesulfonate. It isnoteworthy that the inventors found polycarboxylate ethersuperplasticizers that are extremely effective as flow control and waterreducing admixtures in conventional cement-based materials and concretewere of little benefit or even disruptive to the flow behavior ofcompositions of this invention. This finding is unexpected andsurprising since polycarboxylate ether based superplasticizers are knownin the art for producing cementitious mixtures possessing extremely goodflow behavior. Surprisingly, addition of polycarboxylate ethersuperplasticizers in compositions of the invention was found to increasecoating viscosity and (Sheen Cup) flow time substantially.

The carboxylic acids and/or salts of carboxylic acids used as extendedflow time retention agents of the present invention are other thancopolymerizable unsaturated carboxylic acids and/or salts ofcopolymerizable unsaturated carboxylic acids. For example they are otherthan acrylic acids and/or methacrylic acids or salts thereof.

The carboxylic acids and/or salts of carboxylic acids used as extendedflow time retention agents of the present invention are preferably otherthan copolymerizable unsaturated carboxylic acids and/or salts ofcopolymerizable unsaturated carboxylic acids such as those of structuralformula (IV):

-   -   monocarboxylic acid monomers according to structure (IV):

R³—R⁴—R⁵  (IV)

-   -   wherein:    -   R³ is a moiety having a site of ethylenic unsaturation.    -   R⁴ is absent or is a bivalent linking group, and    -   R⁵ is a moiety that comprises at least one carboxylic acid group        (also known as a carboxyl group (C(O)OH)),

More particularly, the carboxylic acids and/or salts of carboxylic acidsused as extended flow time retention agents of the present invention arepreferably other than copolymerizable unsaturated carboxylic acidsand/or salts of copolymerizable unsaturated carboxylic acids such asthose of structural formula (V):

wherein R⁶, R⁷, R⁸ are H or substituted or unsubstituted functionalgroups, and R⁹ is a functional group containing a carboxyl group(C(O)OH), or polymerized versions thereof, or salts thereof. Thus, forexample, carboxylic acids and/or salts of carboxylic acids used asextended flow time retention agents of the present invention are otherthan methacrylic acid of structural formula (VI):

E. Optional Finish Composition Ingredients

One or more inorganic fillers and aggregates can optionally be includedin the hydrophobic finish composition of some embodiments, e.g., toreduce cost and decrease shrinkage cracking. Typical fillers includesand, talc, mica, calcium carbonate, calcined clays, pumice, crushed orexpanded perlite, volcanic ash, rice husk ash, diatomaceous earth, slag,metakaolin, and other pozzolanic materials. Amounts of these materialsshould not exceed the point where properties such as strength areadversely affected. For example, in some embodiments, the cumulativeamount of aggregate or inorganic filler is about 50% or less by weightof the wet (composition including water) finish composition, such as,for example, about 45% or less, about 30% or less, about 20% or less,about 10% or less, about 5% or less, about 2% or less, about 1% or less,or about 0.1% or less.

In some embodiments, such as when very thin finishes are being prepared,the use of very small fillers, such as sand or microspheres arepreferred. If included, in some embodiments, the filler and/or aggregatepreferably has a particle size of about 3000 microns or less, about 2500microns or less, about 2000 microns or less, about 1500 microns or less,about 1000 microns or less, about 500 microns or less, or about 100microns or less. While not wishing to be bound by any particular theory,it is believed larger particle sizes can sometimes interfere with theprocess for finishing such that uniform coverage may be less apt to beachieved at times.

Water reducing admixture additives optionally can be included inembodiments of the finish composition, such as, for example,superplasticizer, to improve the fluidity of a hydraulic slurry. Suchadditives disperse the molecules in solution so that they move moreeasily relative to each other, thereby improving the flowability of theentire slurry. Sulfonated melamines and sulfonated naphthalenes can beused as superplasticizers, while surprisingly polycarboxylate basedsuperplasticizers are found to be of little benefit or even disruptiveto coating fluidity. Preferred superplasticizers include DILOFLO GWSuperplasticizer of Geo Specialty Chemicals, Cedartown, Ga., andGYPSPERSE from Handy Chemicals, Cleveland, Ohio. The addition of thesematerials allows the user to tailor the fluidity of the slurry to theparticular application.

Water reducing admixture additive can be present in an amount from about0% to about 5% by weight of the wet finish composition. In embodimentsof the invention, the water reducing admixture additive can be, e.g., aslisted in TABLE 6. In the table, an “X” represents the range “from about[corresponding value in first row] to about [corresponding value infirst column].” The indicated values represent percentage by weight ofthe wet finish composition. For ease of presentation, it will beunderstood each value represents “about” that value. For example, thefirst “X” is the range “from about 0% to about 0.5% by weight of the wetfinish composition.”

TABLE 6 0.1 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0.5 X 1 X X 1.5 X X X 2 X X X X2.5 X X X X X 3 X X X X X X 3.5 X X X X X X X 4 X X X X X X X X 4.5 X XX X X X X X X 5 X X X X X X X X X

Colorants optionally can be added to the finish composition to changethe color of the composition or finished articles as desired. Fly ash istypically gray in color, with the Class C fly ash usually lighter thanClass F fly ash. Any dyes or pigments that are compatible with thecomposition may be optionally used. Titanium dioxide is optionally usedas a whitener. A preferred colorant is Ajack Black from SolutionDispersions, Cynthiana, Ky. Colorant can be present in an amount fromabout 0% to about 2% by weight of the wet finish composition, such as,for example, in an amount from about 0.1% to about 2% by weight of thewet finish composition, from about 0.5% to about 2% by weight of the wetfinish composition, from about 1% to about 2% by weight of the wetfinish composition, from about 0.1% to about 1.5% by weight of the wetfinish composition, or about 0.5% to about 1.5% by weight of the wetfinish composition.

F. Fibrous Mat

The fibrous mat comprises any suitable type of polymer or mineral fiber,or combination thereof. Non-limiting examples of suitable fibers includeglass fibers, polyamide fibers, polyaramide fibers, polypropylenefibers, polyester fibers (e.g., polyethylene teraphthalate (PET)),polyvinyl alcohol (PVOH), polyvinyl acetate (PVAc), cellulosic fibers(e.g., cotton, rayon, etc.), and the like, as well as combinationsthereof. Furthermore, the fibers of the mat can be hydrophobic orhydrophilic, finished or unfinished. Of course, the choice of fiberswill depend, in part, on the type of application in which thecementitious article is to be used. For example, when the cementitiousarticle is used for applications requiring heat or fire resistance,appropriate heat or fire resistant fibers should be used in the fibrousmat.

The fibrous mat can be woven or non-woven; however, non-woven mats arepreferred. Non-woven mats comprise fibers bound together by a binder.The binder can be any binder typically used in the mat industry.Suitable binders include, without limitation, urea formaldehyde,melamine formaldehyde, stearated melamine formaldehyde, polyester,acrylics, polyvinyl acetate, urea formaldehyde or melamine formaldehydemodified or blended with polyvinyl acetate or acrylic, styrene acrylicpolymers, and the like, as well as combinations thereof. Suitablefibrous mats include commercially available mats used as facingmaterials for cementitious articles.

By way of further illustration, a non-limiting example of a suitableglass fiber mat comprises about 80-90 percent (e.g., about 83 percent)16 micron diameter, ½-inch to 1-inch long (about 1.2-2.5 cm long)continuous filament fibers and about 10-20 percent (e.g., about 17percent) biosoluble microfibers having about 2.7 nominal micron diameter(MICRO-STRAND Type 481, manufactured by Johns Manville) with a basisweight of about 24 lbs/1000 ft². One suitable glass fiber mat is theDURAGLASS 8924G Mat, manufactured by Johns Manville. Other suitableglass fiber mats are DURAGLASS 8929 Mat, DURAGLASS 7594, DURAGLASS 7524,all from Johns Manville. The binder for the glass mat can be anysuitable binder, for example, styrene acrylic binder, which can be about19-27% (+/−3%) by weight of the mat. The glass mat can include a coloredpigment, for example, green pigment or colorant. The weight of fibrousmat can be between 15-40 lbs/MSF, and the thickness can range between10-40 mils.

The finish material can be applied to the fibrous mat as a liquid orsolid material (e.g., resin, wet-dispersed powder, dry powder, or film)by any of various methods known in the art. For instance, thehydrophobic finish materials can be applied by brushing, spraying,rolling, pouring, dipping, sifting, or overlaying the hydrophobic finishmaterial. Solid materials, such as powders, can be dispersed prior toapplication using any common solvent (e.g., water, alcohols, etc.) ordispersant, provided the solvent or dispersant does not react adverselywith the fibrous mat materials. Solvents that etch surface fibers of thefibrous mat, and thereby enhance the ability of the finish material toadhere to the mat, also can be used. Preferably, any solvent ordispersant used is easily dried and does not leave a residue thatprevents the finish from adhering to the fibrous mat. Liquid ordispersed finish materials can have any viscosity suitable forapplication to the fibrous mat. Typically, the viscosity of a liquid ordispersed finish material will be from about 50-200 Kreb's units (KU)(about 300-20,000 cP), such as about 80-150 KU (about 800-8,000 cP).

Recognizing that the surface of the fibrous mat is an irregular surface,the finish material need not provide a finish that is completelycontinuous. When a liquid or powder finish composition is used, forinstance, the finish material may fall within the voids between thefibers of the mat leaving gaps or holes in the finish. However, thefinish material preferably is applied in an amount sufficient to providea finish that is continuous and, desirably, coextensive with thedimensions of the first fibrous mat.

G. Pre-Coated Fibrous Mat

Preferably the fibrous mat is a pre-coated fibrous mat. By pre-coated itis meant the mat is coated with binder coating before being applied tothe cementitious core material. It will be further understood that inthe ensuing description the terms “web” and “mat” are employedinterchangeably, and in the sense that the mats and webs can be used as“facers”, all three terms may be utilized interchangeably. The coatedglass mat suitable for use, e.g., as a facer in a gypsum board or othercementitious board, is formed by a process which uses a substantiallyporous, predominately glass mat substrate. The glass mat substratecomprises non-woven glass fibers. The binder coating of the coated glassmat advantageously penetrates 10-75% into the thickness of the mat,preferably from approximately 25%-75% of the mat thickness, therebyaffording higher tensile strengths. To whatever depth in this range(10%-75% of the mat thickness) the coating extends, it does soessentially uniformly. The uniformly deep penetration is achieved by oneor more coating techniques described in US published patent applicationno. 2007/0042657 A1 to Bush et al, incorporated herein by reference,which facilitate increased exposure of coating mixture to a glass matsubstrate, thereby achieving more uniform coating penetration. Theuncoated thickness (preferably approximately 25% up to 90% of thethickness) of the glass mat is sufficiently thick for bonding purposeswith the cementitious slurry, such as a gypsum slurry or other slurry ofcementitious core materials.

The raw, uncoated glass mat substrate has a weight between about twelve(12) pounds per thousand square feet and about fifty (50) pounds perthousand square feet. The coating is present in an amount of about 40lbs/MSF to about 165 lbs/MSF, preferably 50-100 lbs/MSF, more preferably61 to 75 lbs/MSF, and being only partially permeated into the glass matsubstrate. On average, the weight of the coated glass mat per unit areais no more than about six times the weight of the glass mat substrateprior to coating. The coating also preferably imparts a tensile strengthto the coated glass mat which on average is at least 1.33 times greaterthan the tensile strength of the glass mat substrate without thecoating. The porosity of the coated glass mat is sufficiently low thatit is not penetrable by gypsum slurry or other cementitious slurry, yet(in the case of where gypsum slurry is employed) porous enough to allowwater vapor to escape from the gypsum slurry when heated. The porosityof the coated glass mat is porous enough to allow gypsum slurry or othercementitious slurry, to completely cover essentially all exposed,individual glass fibers. Preferably the porosity of the coated glass matis in a range of from about 1.3 CFM (cubic feet per minute per squarefoot) to about 5.0 CFM.

Suitable fibrous mats include commercially available mats used as facingmaterials for cementitious articles.

Suitable polymer binders for the binder coating include, withoutlimitation, the above described urea formaldehyde, melamineformaldehyde, stearated melamine formaldehyde, polyester, acrylics,polyvinyl acetate, urea formaldehyde or melamine formaldehyde modifiedor blended with polyvinyl acetate or acrylic, styrene acrylic polymers,and the like, as well as combinations thereof.

Commonly used monomers for the coating polymer are butyl acrylate,methyl methacrylate, ethyl acrylate and the like. Preferably, themonomers include one or more monomers selected from the group consistingof n-butyl acrylate, methyl methacrylate, styrene, and 2-ethylhexylacrylate.

The coating polymer is preferably derived from at least one acrylicmonomer selected from the group consisting of acrylic acid, acrylic acidesters, methacrylic acid, and methacrylic acid esters. For example, thepolymer can be a butyl acrylate/methyl methacrylate copolymer or a2-ethylhexyl acrylate/methyl methacrylate copolymer. For example, the atleast one polymer can be a butyl acrylate/methyl methacrylate copolymeror a 2-ethylhexyl acrylate/methyl methacrylate copolymer. Typically, theat least one polymer is further derived from one or more monomersselected from the group consisting of styrene, alpha-methyl styrene,vinyl chloride, acrylonitrile, methacrylonitrile, ureido methacrylate,vinyl acetate, vinyl esters of branched tertiary monocarboxylic acids,itaconic acid, crotonic acid, maleic acid, fumaric acid, ethylene, andC4-C8 conjugated dienes such as 1,3-butadiene, isoprene or chloroprene.

For example, the coating polymer can be a pure acrylic, a styreneacrylic, a vinyl acrylic or an acrylated ethylene vinyl acetatecopolymer.

The pure acrylics preferably comprise acrylic acid, methacrylic acid, anacrylate ester, and/or a methacrylate ester as the main monomers). Thestyrene acrylics preferably comprise styrene and acrylic acid,methacrylic acid, an acrylate ester, and/or a methacrylate ester as themain monomers. The vinyl acrylics preferably comprise vinyl acetate andacrylic acid, methacrylic acid, an acrylate ester, and/or a methacrylateester as the main monomers. The acrylated ethylene vinyl acetatecopolymers preferably comprise ethylene, vinyl acetate and acrylic acid,methacrylic acid, an acrylate ester, and/or a methacrylate ester as themain monomers. The monomers can also include other main monomers such asacrylamide and acrylonitrile, and one or more functional monomers suchas itaconic acid and ureido methacrylate, as would be readily understoodby those skilled in the art. In a particularly preferred embodiment, thefilm-forming polymer is a pure acrylic such as a butyl acrylate/methylmethacrylate copolymer derived from monomers including butyl acrylateand methyl methacrylate.

Preferably the polymer binder is a latex, most preferably acrylic latex.A latex is a stable dispersion (emulsion) of polymer microparticles inan aqueous medium. Examples of polymer latex binders used with theinorganic fillers are, but are not limited to: Styrene-Butadiene-Rubber(SBR), Styrene-Butadiene-Styrene (SBS), Ethylene-Vinyl-Chloride (EVCI),Poly-Vinylidene-Chloride (PVdC), modified Poly-Vinyl-Chloride (PVC),Poly-Vinyl-Alcohol (PVOH), Ethylene-Vinyl-Actate (EVA),Poly-Vinyl-Acetate (PVA), and Styrene-Acrylate (SA). No asphalt is usedas a binder in this invention. The latex binder (polymer) of the coatingmay comprise polymers derived from versatic acid and/or versatic acidesters as disclosed by US published patent application 2010/0087114 toBush et al incorporated herein by reference. A suitable latex may alsobe one comprising carboxylated styrene butadiene (SBR).

Synthetic latexes are typically made by emulsion polymerization.Emulsion polymerization is a type of radical polymerization that usuallystarts with an emulsion incorporating water, monomer, and surfactant.For example, synthetic latexes suitable for use in the present coatingsacrylates are made by polymerizing a monomer such as acrylic acidemulsified with surfactants to make a an acrylic latex binder,preferably an acrylic latex polymer binder comprised of an acrylic orvinyl ester of a versatic acid isomer.

The most common type of emulsion polymerization is an oil-in-wateremulsion, in which droplets of monomer (the oil) are emulsified (withsurfactants) in a continuous phase of water. Water-soluble polymers,such as certain polyvinyl alcohols or hydroxyethyl celluloses, can alsobe used to act as emulsifiers/stabilizers. Although termed “emulsionpolymerization”, rather than occurring in emulsion droplets,polymerization takes place in the latex particles that formspontaneously in the first few minutes of the process. These latexparticles are typically 100 nm in size, and are made of many individualpolymer chains. The particles are stopped from coagulating with eachother because each particle is surrounded by the surfactant; the chargeon the surfactant repels other particles electrostatically.

Coating techniques of US published patent application no. 2007/0042657A1 to Bush et al, incorporated herein by reference, facilitate increasedexposure of the coating mixture to a glass mat substrate, and thereby auniformly deeper penetration of the coating into the interior spaces ofthe glass mat. The penetration is to a depth of at least 25%, butpreferably less than about 75%, of the thickness of the mat, i.e., notso far that it penetrates entirely. Such increased exposure anduniformly deep penetration is accomplished by various techniquesincluding but not limited to those hereinafter specifically described byUS published patent application no. 2007/0042657 A1 to Bush et al.

Preferably the coating for pre-coating the glass mat contains fillermaterials containing some naturally occurring inorganic binder. Thesefillers with naturally occurring binders must be of a suitable meshsize. The minimum allowable quality is where at least 85% by weight ofthe filler passes a 200-mesh screen (Grade 85/200).

The inorganic filler, gypsum, can be both a mineral pigment (as gypsumdihydrate) and a binder (as gypsum hemi-hydrate).

Examples of the inorganic binders useful with the latex binders in thecoatings of pre-coated glass fiber mats employed in this invention are,but are not limited to the following: calcium oxide, calcium silicate,limestone containing quicklime (CaO), clay containing calcium silicate,sand containing calcium silicate, aluminum trihydrate containingaluminum oxide, and magnesium oxide containing either the sulfate orchloride of magnesium, or both, calcium sulfate hemi-hydrate, magnesiumoxychloride, magnesium oxysulfate, and other complexes of some Group IIAelements (alkaline earth metals), as well as aluminum hydroxide. Oneexample of such a complex inorganic binder is common Portland cement,which is a mixture of various calcium-aluminum silicates. However,Portland cement cures by hydration, which can create a coating mixturewith a short shelf life. Also, both the oxychloride and the oxysulfateof magnesium are complex inorganic binders which cure by hydration. Sucha coating must be used quickly or could set up hard. The oxychloride oroxysulfate of magnesium, aluminum hydroxide, and calcium silicate areonly very slightly soluble in water, and are useful binders of thisinvention. Inorganic binders which are quickly soluble in water, such assodium silicate, are presently not thought to be usable in hostileweather for long periods. The preferred inorganic binder of thisinvention is quicklime, which does not hydrate in a coating mix, butcures by slowly converting to limestone by adding carbon dioxide fromthe air, and thus is not soluble in water.

Examples of inorganic pigments useful with the latex binders in thecoatings of pre-coated glass fiber mats employed in this invention are,but are not limited to: ground limestone (calcium carbonate), clay,sand, mica, talc, gypsum (calcium sulfate dihydrate), aluminumtrihydrate (ATH), antimony oxide, microspheres, pumice, crushed orexpanded perlite, volcanic ash, rice husk ash, diatomaceous earth, slag,metakaolin, fly ash and other pozzolanic materials, or a combination ofany two or more of these substances.

The binder coating comprises 3 to 10 wt % polymer and 90 to 97 wt. %inorganic filler on a water free basis, preferably 4 to 7 wt % polymerand 93 to 96 wt. % inorganic filler on a dry (in other words water free)basis. Typically the filler is about 90 wt. % to 95 wt. % of the bindercoating.

The weight of pre-coated glass mat is typically 50-215 lbs./MSF, and thethickness is 15-65 mils. Suitable pre-coated glass mats include WT ES9000 series and WT PS-1G 9000 series coated glass facers from Atlas WebTechnologies/WEBTECH®, Meridian, Miss.

H. Product Structure

The hydrophobic finish applied to the first fibrous mat is preferably inthe form of a layer. The layer, desirably, is thick enough to slow orprevent the penetration of cementitious slurry through the fibrous matduring production.

The finish desirably has a degree of hydrophobicity such that waterapplied to the finish surface exhibits a contact angle of about 30° orgreater (e.g., about 40° or greater), such as about 30° to about 120°,or about 50° to about 100° The contact angle can be measured by anysuitable technique.

The uncoated mat and hydrophobic finish together can form a composite ofdesired density and thickness. Advantageously, the hydrophobic finish ofembodiments of the invention provides the aforesaid water resistance andaforesaid mechanical properties while using low amounts of finish andsmall thickness of finish, due to the surprising synergistic effect ofthe ingredients in the finish. For example, in some embodiments, thethickness of the finished fiber mat composite can be from about 0.0075inches to about 0.040 inches (7.5-40 mil), such as from about 0.0100 toabout 0.030 inches (10-30 mil), or from about 0.0125 to about 0.020inches (12.5-20 mil). In embodiments of the invention, the thickness ofthe finished fiber mat composite can be, e.g., as listed in TABLE 7A andTABLE 7B below. In the tables, an “X” represents the range “from about[corresponding value in first row] to about [corresponding value infirst column].” The indicated values represent thickness of the finishedfiber mat composite in inches. For ease of presentation, it will beunderstood each value represents “about” that value. For example, thefirst “X” in TABLE 7A is the range “0.0075 inches to about 0.0100inches.”

TABLE 7A 0.0075 0.1 0.0125 0.015 0.0175 0.02 0.01 X 0.0125 X X 0.015 X XX 0.0175 X X X X 0.02 X X X X X 0.0225 X X X X X X 0.025 X X X X X X0.0275 X X X X X X 0.03 X X X X X X 0.325 X X X X X X 0.035 X X X X X X0.0375 X X X X X X 0.04 X X X X X X

TABLE 7B 0.0225 0.025 0.0275 0.03 0.0325 0.035 0.0375 0.025 X 0.0275 X X0.03 X X X 0.0325 X X X X 0.0375 X X X X X 0.04 X X X X X X X

Thus, the thickness of the finished fiber mat composite can have a rangebetween and including any of the aforementioned endpoints set forth inTABLE 7A or TABLE 7B.

Density of the finished fiber mat composite, in some embodiments thatemploy the non-pre-coated fiber mat with the hydrophobic finishcomposition can be from about 65 pcf (pounds per cubic foot) to about125 pcf, preferably about 75 pcf to about 115 pcf, or from about 80 pcfto about 120 pcf. In these embodiments of the invention, the density ofthe finished non-pre-coated fiber mat composite can be, e.g., as listedin TABLE 8 below. In the table, an “X” represents the range “from about[corresponding value in first row] to about [corresponding value infirst column].” The indicated values represent density of the finishedmat composite in lbs./cu.ft. For ease of presentation, it will beunderstood that each value represents “about” that value. For example,the first “X” is the range “65 pcf to about 70 pcf.”

TABLE 8 65 70 75 80 85 90 95 100 105 110 115 120 70 X 75 X X 80 X X X 85X X X X 90 X X X X X 95 X X X X X X 100 X X X X X X X 105 X X X X X X XX 110 X X X X X X X X X 115 X X X X X X X X X X 120 X X X X X X X X X XX 125 X X X X X X X X X X X X

Thus, the density of the finished fiber mat composite can have a rangebetween and any of the aforementioned endpoints.

In some embodiments, the hydrophobic finish composition weight can befrom about 40 lb/MSF (pounds per thousand square feet) to about 200lb/MSF, such as from about 60 lb/MSF to about 160 lb/MSF, or from about80 lb/MSF to about 120 lb/MSF. In embodiments of the invention, thefinish weight can be, e.g., as listed in TABLE 9 below. In the table, an“X” represents the range “from about [corresponding value in first row]to about [corresponding value in first column].” The indicated valuesrepresent finish weight in lb/MSF. For ease of presentation, it will beunderstood that each value represents “about” that value. For example,the first “X” is the range “40 lb/MSF to about 50 lb/MSF.”

TABLE 9 40 50 60 70 80 90 100 105 110 120 130 140 150 160 170 180 190 50X 60 X X 70 X X X 80 X X X X 90 X X X X X 100 X X X X X X 110 X X X X XX X 120 X X X X X X X X 130 X X X X X X X X X 140 X X X X X X X X X X X150 X X X X X X X X X X X X 160 X X X X X X X X X X X X X 170 X X X X XX X X X X X X X X 180 X X X X X X X X X X X X X X X 190 X X X X X X X XX X X X X X X X 200 X X X X X X X X X X X X X X X X X

Thus, the finish weight can have a range between and including any ofthe aforementioned endpoints.

Surprisingly, in embodiments employing the non-pre-coated mat (in otherwords not employing the pre-coated mat), the finish composition isparticularly efficient in promoting water resistance and/or waterbarrier, while achieving or maintaining mechanical properties, andwithout requiring significant amount of finish, in accordance withembodiments of the invention, because the hydrophobic finishsubstantially penetrates the uncoated (non-pre-coated) mat. For example,in some embodiments, the finish penetration depth can be at least about60% of fiber mat thickness, such as a penetration of at least about 70%,or at least about 80% of fiber mat thickness. In embodiments of theinvention employing the uncoated mat, the finish penetration depth canbe, e.g., as listed in TABLE 10 below. In TABLE 10, an “X” representsthe range “from about [corresponding value in first row] to about[corresponding value in first column].” The indicated values representthe percentage of the mat thickness that is penetrated. For ease ofpresentation, it will be understood that each value represents “about”that value. For example, the first “X” is the range “greater than about60% of fiber mat thickness to an amount greater than about 65% of fibermat thickness.”

TABLE 10 60 65 70 75 80 85 65 X 70 X X 75 X X X 80 X X X X 85 X X X X X90 X X X X X X

Thus, the finish penetration depth can have a range between andincluding any of the aforementioned endpoints.

The pre-coated glass mat and hydrophobic finish coating will form alayer with negligible penetration of the hydrophobic finish into theglass mat. The thickness of the finished fiber mat composite can be fromabout 0.018 inches to about 0.080 inches (18-80 mil), preferably fromabout 0.025 to about 0.070 (25-70 mil) inches, or from about 0.040 toabout 0.060 inches (40-60 mil).

In preferred embodiments with pre-coated glass mat, the hydrophobicfinish composition weight on the pre-coated mat is from about 40lbs./MSF (pounds per thousand square feet) to about 200 lbs./MSF, morepreferably from about 50 lbs./MSF to about 100 lbs./MSF, most preferably61 lbs./MSF to 75 lbs./MSF.

Advantageously, the hydrophobic coating stays fluid and workable for atleast 30 minutes without significant stiffening up. The combination ofextended flow time retention agents in the finish is desirable. Theinvention achieves this advantage under ambient conditions and atelevated temperature. For example, in some embodiments, the finishsetting and drying time (under ambient condition of 75° F./50% RelativeHumidity (RH)) can be about 30 to about 60 minutes (e.g., about 30 toabout 50 minutes, about 30 to about 45 minutes, about 30 to about 40minutes, or about 30 to about 35 minutes). In embodiments of theinvention, the finish setting and drying time (under ambientcondition-75° F./50% RH) can be, e.g., as listed in TABLE 11 below. InTABLE 11, an “X” represents the range “from about [corresponding valuein first row] to about [corresponding value in first column].” Theindicated values represent the number of minutes for the finish to setand dry. For ease of presentation, it will be understood each valuerepresents “about” that value. For example, the first “X” is the range“from about 30 minutes to about 35 minutes.”

TABLE 11 30 35 40 45 50 55 35 X 40 X X 45 X X X 50 X X X X 55 X X X X X60 X X X X X X

Thus, the finish setting and drying time (under ambient condition-75°F./50% RH) can have a range between and including any of theaforementioned endpoints.

I. Cementitious Article, Cementitious Board

The cementitious article of the present invention has a cementitiouscore. The cementitious core can comprise any material, substance, orcomposition containing or derived from gypsum and/or hydraulic cement,along with any suitable additives. Non-limiting examples of materialsthat can be used in the cementitious core include Portland cement,sorrel cement, slag cement, fly ash cement, calcium alumina cement,water-soluble calcium sulfate anhydrite, calcium sulfate α-hemihydrate,calcium sulfate β-hemihydrate, natural, synthetic or chemically modifiedcalcium sulfate hemihydrates, calcium sulfate dihydrate (“gypsum,” “setgypsum,” or “hydrated gypsum”), and mixtures thereof. As used herein,the term “calcium sulfate material” refers to any of the forms ofcalcium sulfate referenced above. In gypsum boards, calcium sulfatehemihydrate upon reaction with water eventually gets converted tocalcium sulfate dihydrate. However, gypsum boards can contain somecalcium sulfate hemihydrate which is formed due to overheating anddehydration of calcium sulfate dihydrate in the kiln.

The additives for the cementitious core can be any additives commonlyused to produce cementitious articles, such as gypsum board or cementboard. Such additives include, without limitation, structural additivessuch as mineral wool, continuous or chopped glass fibers (also referredto as fiberglass), perlite, clay, vermiculite, calcium carbonate,polyester, and paper fiber, as well as chemical additives such asfoaming agents, fillers, accelerators, sugar, enhancing agents such asphosphates, phosphonates, borates and the like, retarders, binders(e.g., starch and latex), colorants, fungicides, biocides, and the like.Examples of the use of some of these and other additives are described,for instance, in U.S. Pat. Nos. 6,342,284, 6,632,550, 6,800,131,5,643,510, 5,714,001, and 6,774,146, and U.S. Patent Publications2004/0231916 A1, 2002/0045074 A1 and 2005/0019618 A1.

Preferably, the cementitious core comprises a calcium sulfate material,Portland cement, or mixture thereof. Advantageously, if desired, in someembodiments, the cementitious core also comprises a hydrophobic agent,such as a silicone-based material (e.g., a silane, siloxane, orsilicone-resin matrix), in a suitable amount to improve the waterresistance of the core material. It is also preferred that thecementitious core comprise a siloxane catalyst, such as magnesium oxide(e.g., dead burned magnesium oxide), fly ash (e.g., Class C fly ash), ora mixture thereof. The siloxane and siloxane catalyst can be added inany suitable amount, and by any suitable method as described herein withrespect the method of preparing a water-resistant cementitious articleof the invention, or as described, for example, in U.S. PatentPublications 2006/0035112 A1 or 2007/0022913 A1. Desirably, thecementitious core also comprises strength-improving additives, such asphosphates (e.g., polyphosphates as described in U.S. Pat. Nos.6,342,284, 6,632,550, and 6,800,131 and U.S. Patent Publications2002/0045074 A1, 2005/0019618 A1, and 2007/0022913 A1) and/orpre-blended unstable and stable soaps (e.g., as described in U.S. Pat.Nos. 5,683,635 and 5,643,510).

The cementitious core can comprise paper or glass fibers, but ispreferably substantially free of paper and/or glass fibers (e.g.,comprises less than about 1 wt. %, less than about 0.5 wt. %, less thanabout 0.1 wt. %, or even less than about 0.05 wt. % of paper and/orglass fibers, or contains no such fibers), wherein the wt. % is basedupon weight of the cementitious core on a water free (dry) basis. Forthe purposes herein, the core can include one or more dense skim coatsand/or hard edges, as is known in the art.

The cementitious article can be any of any type or shape suitable for adesired application. Non-limiting examples of cementitious articlesinclude gypsum panels (also known as gypsum boards or gypsum basedboards) and cement panels (also known as cement panels or cement basedboards) of any size and shape. The term cementitious panel encompassesboth a gypsum panel and a cement panel. A gypsum panel has over 50 wt. %gypsum in its core on a dry basis. A cement panel has over 20% Portlandcement in its core on a dry basis. Optionally a cement panel furthercomprises gypsum and other additives.

In addition to boards the compositions of the hydrophobic finish coatingof present invention are useful as waterproof tile membranes forinstallation of tiles on floors and walls; waterproof roofing membranes;waterproof coatings for use over concrete floors and walls in interiorapplications; exterior waterproof coatings for use over concrete roofs,walls, balconies and foundations; exterior waterproof coatings for walland roof sheathings; air and water barriers for exterior walls androofs; colored and decorative coatings; fire-retardant coatings;coatings applied over wood-based materials, metals and plastics; crackfilling and other construction repair products; skim-coat and patchproducts; statuary products.

FIG. 1 shows a schematic of a board 2 of the present invention. Theboard 2 comprises a cementitious core 10, two fibrous mats 20, and twocoatings 30 of hydrophobic finish composition.

The article can also be a poured, preferably self-leveling, flooringcomposition, for example a flooring underlayment, having thecementitious layer and the hydrophobic finish facing the cementitiouslayer. FIG. 1A illustrates a schematic diagram of a compositeunderlayment 14 of the present invention comprising a cementitious layer12 and a coating 32 of the hydrophobic finish composition. Thecementitious layer is typically a cement-based layer or a gypsum basedlayer. The term cementitious layer encompasses both a gypsum layer and acement layer. A gypsum layer has over 50 wt. % gypsum in on a dry basis.A cement layer has over 20% Portland cement on a dry basis. Optionallythe cement layer comprises gypsum and other additives.

Also, the finish composition is useful to give favorable properties toone or more sides of an article. A finish for use as an underlayment ofceramic tile can be prepared preferably by rolling or screeding thehydrophobic finish composition of the invention onto a reinforcingfibrous basemat or scrim. The coated product in the form of a membranecan then be used as a substrate on floors and walls for installation ofceramic tiles and synthetic stones. Statuary or architectural moldingscould be made of a different core, then finished with sufficientthickness of this composition to allow the piece to be shaped, carved,fit or detailed using common tools.

Product according to some embodiments of the invention achievesdesirable strength and flexibility properties in addition to the waterresistance and/or waterproofness properties. To this end, productaccording to embodiments of the invention achieves water resistance andwater impermeability without becoming undesirably too brittle orotherwise compromising strength.

Thus, in some embodiments (embodiments having non-pre-coated fibrousmats and embodiments with pre-coated fibrous mats), product according tothe invention meets the product specifications set forth in ASTMC1178/C1178M-13, ASTM C1177/C1177M-13, and ASTM C1658/C1658M-13. Forexample, with respect to nail pull resistance, product according to someembodiments of the invention have a nail pull resistance of at leastabout 40 pounds, such as at least about 70 pounds, or at least about 90pounds. The nail pull spec in ASTM C1178 is >70 lb for ½″, and in ASTMC1177 & ASTM C1658 is >80 lb for ½″. The nail pull resistance may varydepending on the thickness of a board. In the case of ¼″ boardthickness, the nail pull resistance in accordance with embodiments ofthe invention is at least about 40 pounds. In the case of ½″ boardthickness, the nail pull resistance, in accordance with some embodimentsof the invention is at least about 70 pounds. In the case of ⅝″ boardthickness, the nail pull resistance in accordance with some embodimentsof the invention is at least about 90 pounds.

Product according to embodiments of the invention (embodiments havingnon-pre-coated fibrous mats and embodiments with pre-coated fibrousmats) also exhibit desirable flexural strength properties. For example,in some embodiments, the flexural strength is at least about 40 pounds(e.g., at least about 80 pounds, or at least about 100 pounds) bearingedges parallel to the board edge, or at least about 50 pounds (e.g., atleast about 100 pounds, or at least about 140 pounds) bearing edgesperpendicular to the board edge. The flexural strength may varydepending on board thickness. In the case of ¼″ board thickness, theflexural strength in some embodiments is at least about 40 poundsbearing edges parallel to the board edge, and/or about 50 pounds bearingedges perpendicular to the board edge. In the case of ¼″ boardthickness, the flexural strength in some embodiments is at least about80 pounds bearing edges parallel to the board edge, and/or at leastabout 100 pounds bearing edges perpendicular to the board edge. In thecase of ⅝″ board thickness, the flexural strength in some embodiments isat least about 100 pounds bearing edges parallel to the board edge,and/or at least about 140 pounds bearing edges perpendicular to theboard edge.

Product according to the invention also achieves desirable core, end,and edge hardness, as well as desirable surface water absorption,humidified deflection, and shear bond strength. For example, in someembodiments, the average core, end, and edge hardness is at least about15 pounds. The average surface water absorption of the face side of theboard in some embodiments is not more than about 1.6 grams after 2 hoursof elapsed time in accordance with ASTM C1658, or is not more than 0.50grams after 2 hours of elapsed time in accordance with ASTM C1658.Regarding humidified deflection, the average deflection of the boards insome embodiments is not more than about 2 inches, such as not more thanabout 1 inch, preferably more than about ¼ inches, such as not more thanabout ⅛ inch. The humidified deflection may vary depending on boardthickness. In the case of the ½″ thick board, in some embodiments, theaverage humidified deflection is not more than about 2 inches. In thecase of ⅝ ″ thick board, the average humidified deflection is not morethan about 1 inch, preferably ¼ inches. In the case of ⅝″ thick board,the average humidified deflection is not more than about ⅛ inch. Theshear bond strength in some embodiments of the invention is at leastabout 50 psi when tested in accordance with ASTM C1325. In someembodiments, the finish composition has a pH of at least about 9, suchas at least about 9.5, or at least about 10.

In an embodiment, when the board is cast as ½″ thick board (overallboard thickness, not merely the core), the board has a nail pullresistance of at least about 70 pounds in accordance with ASTMC1178/C1178M-13.

In another embodiment, when the board is cast as ½″ thick board (overallboard thickness, not merely the core), the board has a nail pullresistance of at least about 80 pounds in accordance with ASTMC1177/C1177M-13 and ASTM C1658/C1658M-13.

In another embodiment, when the board is cast as ½″ thick board, theboard has a flexural strength of at least about 80 pounds bearing edgesparallel to the board edge and/or at least about 100 pounds bearingedges perpendicular to the board edge, in accordance with ASTMC1178/C1178M-13, ASTM C1177/C1177M-13, or ASTM C1658/C1658M-13.

In a preferred embodiment to improve water resistance and permit use ofrelatively less hydrophobic finish composition and potentially less orno silane, the fibrous mat for surface reinforcing the inorganiccementitious panel is the above-described fibrous mat pre-coated with abinder coating. This results in a mat-faced cementitious boardcomprising, consisting of, or consisting essentially of

-   -   the above described cementitious-based core,    -   the fibrous mat comprising a glass mat substrate having        non-woven glass fibers, a binder coating on a side of the mat,        the binder coating comprising polymer binder and inorganic        filler, wherein the inorganic filer is selected from at least        one member of the group consisting of inorganic pigment and        inorganic binder, the binder coating is present in an amount of        about 40 lbs/MSF to about 165 lbs/MSF, more preferably about 50        lbs/MSF to about 100 lbs/MSF, and most preferably about 61        lbs/MSF to about 75 lbs/MSF, wherein the coating uniformly        penetrates the glass mat substrate from one side of the coated        glass mat to a depth which is a fraction of the thickness of the        coated glass mat, and    -   a layer of the above described hydrophobic finish composition,        wherein the above described hydrophobic finish composition        optionally comprises silane,    -   wherein the layer of the above described hydrophobic finish        composition adheres to the side of the fibrous mat coated with        the binder coating and the cementitious-based core adheres to        the opposed side of the fibrous mat.

The hydrophobic finish composition layer is adhered to the coatedsurface of the coated fibrous mat rather than the raw glass fiber side.The cementitious-based core is adhered to the raw glass fiber side. Thehydrophobic finish of this embodiment optionally comprises silane.However, a presence of silane is preferred if additional waterresistance is desired. An absence of silane is preferred for reducingproduction costs.

FIG. 14 shows a schematic of a board 302 of the present inventionemploying pre-coated glass mat. The board 302 comprises a cementitiouscore 310, two pre-coated fibrous mats 320 comprising coated portion 322coated with polymer and uncoated portion 326, as well as two coatings330 of hydrophobic finish composition.

FIG. 14A illustrates a schematic diagram of a board 314 of the presentinvention comprising a cementitious, one fibrous mat 320 comprisingcoated portion 322 coated with polymer and uncoated portion 326, as wellas a coating 332 of the hydrophobic finish composition. The cementitiouslayer 312 is typically a cement-based layer or a gypsum based layer. Theterm cementitious layer encompasses both a gypsum layer and a cementlayer. A gypsum layer has over 50 wt. % gypsum in on a dry basis. Acement layer has over 20% Portland cement on a dry basis. Optionally thecement layer comprises gypsum and other additives.

FIG. 15 depicts a cross section of a coated glass mat 320 for use in thepresent invention. The thickness dimension (represented by referencenumeral 324A) of the coated portion 324 of coated glass mat 320 is about0.002-0.050 inches (2-50 mil). The measured thickness of the coatingpenetration for the coated portion 322 is depicted by arrow 322A, whilethe thickness of the portion 326 remaining uncoated is labeled by arrow326A. These dimensions particularly apply to a coated portion extending10-75% through the thickness of a coated mat wherein the mat thicknessis 0.015-0.065 (15-65 mil).

The product employing the pre-coated mat can be, for example, exteriorsheathing panels, tile backer board, floor underlayment, roof board, orinterior wall and ceiling boards, for example the coated board can beused as interior boards with paint or other drywall finishes, ceilingwith or without tiles),

J. Water Resistance

Preferably the surface water absorption of the cementitious boards ofthe present invention is less than 1.6 grams, more preferably less than0.5 grams, furthermore preferably less than 0.45 grams, stillfurthermore preferably less than 0. grams, and most preferably less than0.3 grams, as measured in accordance to ASTM C473. <1.6 g is measuredper ASTM C1658. <0.5 g, <0.45 and <0.4 are measured per ASTM C1178.

Embodiments of the present invention impart an improved waterresistance, such as for mat-faced applications, and in some embodiments,the product of the invention can achieve substantial impermeability towater to allow for water barrier properties. Preferably boards accordingto the present invention pass the test for waterproofness under theAmerican National Standards Institute (ANSI) standard ANSI A118.10(revised, October 2008), which modifies ASTM D4068-09 (Annex 2:Hydrostatic Pressure Test). The waterproof test is conducted with ahydrostatic head of 24 inches on the sample. The product according tothe invention not only exhibits desirable water resistance properties,but also in some embodiments exhibits waterproofness. As such, productaccording to embodiments of the invention is useful in applicationswhere such water impermeability property is particularly desirable, asdescribed herein. Passing the waterproofness standard advantageously canallow product in accordance with embodiments of the invention to be usedin areas subject to waterproof standards under international buildingand residential codes.

K. Method of Preparing the Cementitious Article

The cementitious article according to the invention can be prepared,including application of the above-described hydrophobic finishcomposition to form a composite, by any suitable method including, butnot limited to, the inventive methods described herein, and, e.g., asdescribed in corresponding, commonly-assigned U.S. patent applicationSer. No. 13/837,041, filed Mar. 15, 2013, entitled “Method of PreparingMat-Faced Article,” (US Patent Application Publication No. 2014/0261954)and commonly-assigned U.S. patent application Ser. No. 13/835,556, filedMar. 15, 2013, entitled “Cementitious Article Comprising HydrophobicFinish,” (US Patent Application Publication No. 2014/0272402) both ofwhich are incorporated herein by reference.

Embodiments of a method of preparing a fibrous mat-faced cementitiousarticle according to the invention comprise (a) depositing acementitious slurry on a first fibrous mat comprising woven or non-wovenpolymer fibers or mineral fibers, (b) depositing a second fibrous mat ontop of cementitious slurry, (c) allowing the cementitious slurry toharden, thereby providing a fibrous mat-faced cementitious article, (d)applying the hydrophobic finish on one or both surfaces of the fibrousmat-faced cementitious article.

The method of preparing a cementitious article in accordance with theinvention can be conducted on existing gypsum board manufacturing linesused to make fibrous mat-faced cementitious articles known in the art.Briefly, the process typically involves discharging a fibrous matmaterial onto a conveyor, or onto a forming table that rests on aconveyer, which is then positioned under the discharge conduit (e.g., agate-canister-boot arrangement as known in the art, or an arrangement asdescribed in U.S. Pat. Nos. 6,494,609 and 6,874,930) of a mixer. Thecomponents of the cementitious slurry are fed to the mixer comprisingthe discharge conduit, where they are agitated to form the cementitiousslurry. Foam can be added in the discharge conduit (e.g., in the gate asdescribed, for example, in U.S. Pat. Nos. 5,683,635 and 6,494,609). Thecementitious slurry is discharged onto the fibrous mat facing material.The slurry is spread, as necessary, over the fibrous mat facing materialand optionally covered with a second facing material, which may be afibrous mat or other type of facing material (e.g., paper, foil,plastic, etc.). The wet cementitious assembly thereby provided isconveyed to a forming station where the article is sized to a desiredthickness, and to one or more knife sections where it is cut to adesired length to provide a cementitious article. The cementitiousarticle is allowed to harden, and, optionally, excess water is removedusing a drying process (e.g., by air-drying or transporting thecementitious article through a kiln). Each of the above steps, as wellas processes and equipment for performing such steps, are known in theart. It also is common in the manufacture of cementitious articles suchas gypsum and cement board to deposit a relatively dense layer of slurryonto a facing material before depositing the primary slurry, and to usevibration to eliminate large voids or air pockets from the depositedslurry. Also, hard edges, as known in the art, are sometimes used. Thesesteps or elements (dense slurry layer, vibration, and/or hard edges)optionally can be used in conjunction with the invention. An aqueoushydrophobic finish composition is applied to the outside mat surface toform the mat-faced cementitious article composite.

To make the hydrophobic finish coating, the polymer may be added as adispersion including from about 30 to about 75% solids and a meanpolymer particle size of from about 70 to about 650 nm. The polymer ispreferably present in the aqueous coating composition in an amount fromabout 5 to about 60 percent by weight, and more preferably from about 8to about 40 percent by weight.

All aspects of the fibrous mat, core ingredients, and hydrophobic finishcomposition ingredients used in accordance with the method of preparinga cementitious article are as described by the present specificationwith respect to the cementitious article of the invention.

In one aspect, the mat-faced gypsum article comprises a mat having aninner surface adjacent to a cementitious core and an opposite outersurface. An aqueous hydrophobic finish composition is applied to theoutside surface to form the mat-faced cementitious article composite.Desirably, the hydrophobic finish composite can suitably be applied by aroller assembly (such as that of US Published Patent Application No.2014/0261954 to Dubey et al) comprising a finish roller. In someembodiments, the finish roller has an uneven surface, including, forexample, grooves or depressions (e.g., circumferential or longitudinal)defined therein.

FIG. 2A shows a schematic side view illustrating a roller assembly formaking a composite board of the present invention comprising a finishroller with circumferential grooves defined therein applying ahydrophobic finish composition to a mat faced cementitious board withthe assembly in a direct finish orientation, in accordance with anembodiment of the invention.

One exemplary embodiment for applying finish composition to a mat-facedboard (e.g., gypsum board) is depicted in FIGS. 2A-2B, which show adirect application orientation of a roller assembly 100 such that afinish roller 110 rotates in the same direction that the mat-faced board112 travels as described below. Thus, the finish roller 110 rotates in adirection so its surface moves in the same direction as the board moves.In contrast, in reverse finishing configurations, described below inconnection with FIGS. 3A-3B, the finish roller rotates in reverse so itssurface in contact with the board is moving in the opposite directionthat the board moves.

Roller assembly 100 also includes a doctor roller 114 which engagesfinish roller 110. Rollers 110 and 114 are mounted with bracketsjournaled to allow for rotation and extend from columns mounted on thebuilding floor or table on which the board travels. One or both of therollers 110 and 114 are driven by a motor. In some embodiments, thefinish roller 110 and doctor roller 114 are driven, e.g., byindependent, variable speed, drive assemblies. This can be advantageousin some embodiments to allow the finish roller 110 speed and doctorroller 114 speeds to be varied independently, as desired. In otherembodiments, one of the rollers 110 or 114 is driven while the otherroller 110 or 114 is an idler such that it rotates by engagement withthe driven roller to rotate in response to the roller being driven.

The doctor roller 114 engages with the finish roller 110. Particularly,the doctor roller 114 mates with the finish roller 110 to form a troughbetween the two, where the finish composition is introduced. The finishroller 110 and the doctor roller 114 generally counter-rotate, i.e.,rotate in opposite directions relative to one another, both in directfinishing or reverse finishing configurations (described below). Havingthe finish roller 110 and doctor roller 114 engage in this mannerfacilitates keeping the slurry for the hydrophobic coating in the gapbetween the two rollers so that so that the slurry for the hydrophobiccoating does not spill. The position of the doctor roller 114 isadjusted relative to the finish roller 110. This may result in a smallgap between the two rollers, which can be adjusted to control the amountof slurry allowed to pass between them, which in turn influences theamount of finishing composition to be applied. In some embodiments,particularly in direct finishing arrangement, this gap may actually benegative indicating an interference fit as that term is understood inthe art, thereby indicating that the doctor roller 114 is touching, andcompressing the surface of, the finish roller 110.

As best seen in FIG. 2B, the finish roller 110 includes grooves 116circumferentially disposed in the surface of the finish roller 110. Inthe direct application orientation, doctor roller 114 is upstream offinish roller 110 to minimize the surface area of finish roller 110bearing the finish composition. In this respect, it has been found thatincreasing the surface area (beyond, e.g., 90 degree, 100 degree, 120degree, etc.) of the portion of finish roller 110 that bears finishcomposition increasingly results in undesirable variation in the finishapplication. A top surface 118 of the board 112 as shown is adjacent tothe finish roller 110. A bottom roller 120 is disposed under a bottomsurface 122 of the board 112. The board is generally supported by aroller conveyor, chain conveyor, belt conveyor, or the like at the passline height, i.e., the same elevation as the top of the bottom roller120. For example, the bottom roller 120 can optionally work in concertwith other rollers which help transport board into and out of theassembly roller 100.

Hydrophobic finish composition is dispensed between finish roller 110and doctor roller 114 to feed the composition between the finish roller110 and doctor roller 114 and onto the surface of the finish roller 110for application to top surface 118 of board 112. A head 124 of thehydrophobic finish composition slurry forms between the doctor roller114 and the finish roller 110. The head can be controlled by sensor suchas laser control as understood in the art. The surface of the finishroller 110 pulls finish composition onto the board 112 to deposit thefinish composition onto the top surface 118 to lay a finish 126 and forma composite 128. The bottom roller 120 provides underlying support andis generally aligned under the finish roller 110.

Another exemplary embodiment for applying a finish composition to amat-faced board (e.g., gypsum board) is depicted in FIGS. 3A-3B, whichshow a reverse application orientation of a roller assembly 200 suchthat a finish roller 210 rotates in the opposite or counter directionthat the mat-faced board 212 travels. Roller assembly 200 includes adoctor roller 214 which engages with finish roller 210 incounter-rotation. As best seen in FIG. 2B, the finish roller 210includes grooves 216 that are circumferentially disposed in the surfaceof the roller 210. In the reverse application orientation, doctor roller214 is downstream of finish roller 210 to minimize the surface area ofthe finish roller 210 that bears the finish composition. A top surface218 of the board 212 as shown is adjacent to the finish roller 210. Abottom roller 220 is disposed under a bottom surface 222 of the board212. The bottom roller 220 may have a cover formed from, for example,rubber or elastomeric material such as neoprene, to achieve traction onthe bottom surface 222, to ensure board travels at the desired speed anddesired direction, despite the frictional force of the finish roll 210.

Finish composition is dispensed between finish roller 210 and doctorroller 214. A head 224 of the hydrophobic finish composition slurryforms between the doctor roller 214 and the finish roller 210. Thefinish roller 210 acts to apply the finish composition onto the topsurface 218 to lay a finish 226 and form a composite 228. Other aspectsof the embodiment set forth in FIGS. 2A-2B, such as driver for the roll,the mounting thereof, and the presence of other bottom rollers, aresimilar to the description set forth relative to FIGS. 1A-1B asdescribed above.

Generally, in both embodiments depicted in FIGS. 2A, 2B, 3A, and 3B,doctor roller 114 or 214 has a smaller diameter than finish roller 110or 210 because the highest elevation of both the doctor roller 114 andfinish roller 110 typically is at the same elevation (or with axes atsubstantially coinciding elevation), and the lowest elevation of thedoctor roller 114 or 214 should be higher than the surface to befinished, to avoid interference with the article being finished. Thegrooves 116 and 216 can be in any suitable configuration. For example,the finish roller 110 or 210 can comprise a buttress thread form todefine the grooves in some embodiments. In embodiments including thebuttress thread configuration, any suitable buttress thread count perlongitudinal inch of the roller can be used.

In these and other embodiments, each roller piece in the roller assemblycan be independently driven and varied to allow fine tuning thefinishing. As noted herein, the bottom roller can optionally be a partof a larger section of rollers used in conveyors for moving board down amanufacturing line. For example, in some embodiments, a series ofrollers can be driven with one drive and linked together (e.g., withchains, belts, or the like). However, in some embodiments, the bottomroller can have its speed independently varied relative to otherconveying rollers to thereby allow more precise control of the bottomroller of the roller assembly of embodiments of the invention, e.g., toregulate the speed of the bottom roller to correspond with the speed ofthe board.

The bottom roller in accordance with embodiments of the invention is asupporting roller opposing the finish roller. For example, the finishroller advantageously can keep the board being treated with finishcomposition at the desired elevation (path line height) while alsoenhancing traction to drive the board in the proper direction andsubstantially constant rate down the manufacturing line. The bottomroller further facilitates having an even finish thickness on the outersurface of the board. For example, the roller reduces the chance forroller slippage over the board to which the finish is being applied.Such slippage can undesirably result in variation in thickness of theapplied finish composition. In some embodiments, as an alternative to abottom roller, a plate such as an anvil plate can be used.

The vertical gap between the finish roller and bottom roller can beadjusted to accommodate different clearances between them, e.g., toaccommodate different board thickness. In some embodiments, the bottomroller remains stationary while the finish roller is moved up and downto adjust the gap. However, other variations are possible, includinghaving the height of the bottom roller adjustable or having both thefinish roller and the bottom roller being adjustable.

The doctor roller typically is formed at least in part with suitablemetal. For example, in some embodiments, the metal is steel such asstainless steel to avoid rusting given that the finish composition isnormally in the form of aqueous slurry. The surface can be plated withchrome or the like to allow the doctor roller to remain as clean aspossible in operation.

The composition of the finish roller may vary, e.g., depending onwhether a direct finishing or reverse finishing arrangement is employed.For example, in some embodiments of a direct finishing arrangement, thefinish roller can be formed of metal with a softer cover such as formedfrom one or more rubbers or elastomeric material such as neoprene,ethylene propylene diene monomer (EDPM) rubber, or the like. In thisrespect, it is understood that the article to be finished, includingmat-faced board, are not perfectly flat because of, e.g., surfaceimperfections. Thus, in accordance with embodiments of the invention, acover (e.g., made of rubber material) can be used to conform to surfaceimperfections in the board or other article to allow for an even morefinish. Rubbers are desirable materials for this purpose because ofcompressibility property and long wear life. They also tend to bematerials that are easy to keep clean. The use of a steel finish rollercan be less desirable in some embodiments of direct finishingarrangements. For example, where surface imperfections are prevalent, asteel finish roller is less apt to conform to the surface. The appliedfinish will have variation with a thicker finish being observed wherethere are depressions in the board surface and a thinner finish observedwhere there are protrusions in the board surface.

However, in some embodiments, such as some reverse finish arrangements,the finish roller can be formed from metal such as steel to reduce wear.In this respect, where the finish roller is rotating in a directionopposite as the board is traveling, the finish roller will exhibitundesirable wear characteristics in operation if the finish roller ismade of softer material such as rubber. Furthermore, a rubber finishroller may at times create excessive traction such that the boardundesirably could be pushed backwards.

It will be understood the grooves, if present, can be in any suitableconfiguration. Grooves advantageously allow for more surface area forfinish to be applied. The grooves can be cut into the rubber coverand/or into a metal roller in various embodiments, with grooves beingparticularly advantageous in rubber covered embodiments of finish rollerbecause rubber in some embodiments is easier to clean. In someembodiments, the finish roller comprises a buttress thread form todefine the grooves in some embodiments. In embodiments including thebuttress thread configuration, any suitable buttress thread count perlongitudinal inch of the roller can be used. For example, in someembodiments, the finish roller has from about 4 to about 50 buttressthread per inch of longitude, such as from about 8 to about 12 buttressthread per inch, e.g., about 10 buttress thread per inch.

In some embodiments, the finish roller has a longitudinal axis and thegroove(s) are circumferential such that they are perpendicular, ornearly perpendicular, to the axis. The grooves can have any suitabledepth, such as a depth from about 0.001 inch to about 0.25 inch, e.g.,from about 0.05 inch to about 0.20 inch. The grooves can have anysuitable width, for example, from about 0.001 inch to about 0.25 inch,such as from about 0.08 inch to about 0.012 inch.

The size of the rollers can vary. For example, the radius of the finishroller is dependent on the line speed of the article being finished, andthe viscosity of the finish composition. The length of the finish rolleris dependent on the width of the panels being finished and normally thelength of the roller is somewhat longer than the width of the product,e.g., 10 to 15% longer, for example, to ensure the product is finishedacross the entire width. The radius of the doctor roller may bedependent on the radius of the finish roller, speed of doctor roller,finish viscosity, etc. In some embodiments, the doctor roller has asmaller diameter than the finish roller so its axis is substantially thesame elevation as the axis of the finish roller, while its bottomsurface is above the top surface of the panel 218. The length of thedoctor roller should normally be the same as the length of the finishroller, with dams on the ends of these rollers, to prevent hydrophobicfinish composition coating from spilling over.

The finish roller is normally fabricated from steel, and can have one ormore covers with any suitable hardness. In some embodiments, thehardness of the finish roller is selected to be softer than the doctorroller to allow the doctor roller to compress the finish roller as therollers engage which is advantageous in controlling the amount of finishcomposition to be deposited. For example, the cover(s) can be such thatthe finish roller can have a hardness of about 100 Durometer or less asdetermined according to Shore-A, such as about 70 Durometer Shore-A orless, e.g., about 40 Durometer Shore-A, with the doctor roller desirablyhaving higher corresponding hardness value than the selected value forthe finish roller in some embodiments. If desired, the finish rollercover(s) comprises neoprene, EPDM, or a combination thereof to helpreduce surface hardness while maintaining a harder core in someembodiments. For direct finish configurations, desirably the finishroller can be formed from rubber in order to allow if to conform to theimperfect surface of the board, resulting in a more uniform finishingthickness. In reverse finish configurations, a roller with no cover canbe used in some embodiments, e.g., a chrome-plated smooth steel finishroller because this allows for greater resistance to wear, while alsominimizing frictional force against the top surface of the board 218,and minimizing the amount of finishing adhering on the roller surface.

The gap between adjacent surfaces of the doctor roller and finish rollerin some embodiments are in an interference fit such that the gap isdefined by a negative number as understood in the art. The negativenumbers refer to the amount of interference, for example, the differencebetween the sum of the outmost radii of the finish roller and the doctorroller, and the actual distance between axes of these two rollers. Insome embodiments where the finish roller is generally softer than thedoctor roller, the doctor roller can compress the finish roller when therolls are positioned this way. The gap between the doctor roller andfinish roller may be adjusted depending on factors including theviscosity of the finishing composition, the speed of the rollers, andwhether direct or reverse roller configurations are employed. In directroller finishing, the finish roller and the doctor roller are disposedto define a gap therebetween in some embodiments from about +0.010 inch(about +0.025 cm) to about −0.020 inch (about −0.051 cm), such as fromabout −0.005 inch (about −0.013 cm) to about −0.010 inch (about −0.025cm), e.g., about −0.007 inch (about −0.018 cm). In reverse finishingarrangements, the gaps can be somewhat larger, e.g., from zero to about+0.010 inch in some embodiments.

In some embodiments, the roller assembly is configured such that a gapbetween the finish roller and the bottom roller is less than the averagepanel thickness by about 0 inch (about 0 cm) to about 0.10 inch (about0.25 cm), such as by about 0.01 inch (about 0.25 cm) to about 0.08 inch(about 0.20 cm), e.g., by about 0.02 inch (about 0.51 cm) to about 0.06inch (about 0.15 cm).

To make the hydrophobic cementitious finish composition, the hydrauliccomponent, polymer, extended flow time retention agent, water, optionalcomponents, and preferably silane compound, are combined in a mixer andmixed until a homogeneous blend is obtained. Preferably, the mixer is ahigh shear mixer providing a short residence time. For small batches ofproduct, a typical laboratory blender is a suitable mixing device. Forlarger industrial operations, the use of commercially availablecontinuous mixers, e.g., as manufactured by the PFT GMBH and Co. KG,based in Iphofen, Germany, are suitable. Continuous mixers have thecapability of mixing and pumping the slurry in a continuous manner tothe point of application. These mixers have a mixing chamber where allsolid dry materials are blended together with the liquid additivesincluding water using a cage agitator rotating at a high speed. In thenormal mode of operation, the blended cementitious slurry continuouslyexits the mixing chamber and is pumped forward by a progressive cavitypump (rotor-stator type pump) to the point of application. The preferredPFT mixer models for this invention include PFT Mixing Pump G4, PFTMixing Pump G5, PFT MONOJET 2.13, PFT Mixing Pump T2E, PFT Mixing PumpMS1 and MS2.

Another preferred mixer is a high-shear batch mixer. The batch mixer ispreferred in some applications, particularly where the slurry must befed to more than one area of the manufacturing line. The wet ingredientsare charged to the mixer, followed by the dry components. After mixing,the entire batch is dumped into a pot for continuous distribution to theline. If distribution to more than one location is desired, multiplepumps with separate destinations can be used to distribute slurry fromthe pot.

After mixing, the flowable slurry exits from the mixer and can be pouredinto a mold or extruder, onto release paper or onto a base mat forshaping into an appropriate shape. Any method may be used to shape thecomposition, including molding, extruding, troweling, calendaring,rolling, screeding, or any shaping method suitable for the article beingproduced.

Methods of applying hydrophobic finish composition also includespraying, curtain coating, and knife coating.

Thus, in an embodiment, a mat-faced gypsum board made as discussed abovecomprises gypsum based core, fibrous mat having an inner surface facingat least one face of the gypsum-based core, and hydrophobic finishcomposition comprising hydraulic component comprising Class C fly ash,film-forming polymer, a silane compound, and an extended flow timeretention admixture. Each of these ingredients, and their preferredembodiments, for use in the method of making the hydrophobic finishcomposition are the same as described by the present specification withrespect to the cementitious article of the invention.

Preferably, the film-forming polymer is in an amount from about 5% toabout 25% by weight of the wet finish. This is weight percent of drypolymer based on total weight of the wet (water included) finishcomposition.

Preferably, the finish has a pH of at least about 9.

Preferably, the fibrous mat comprises polymer or mineral fiber.

Preferably, the polymer or mineral fibers are glass fibers, polyesterfiber, or any combination thereof.

Preferably, the fibrous mat is pre-coated with binder coating.

Preferably, the not pre-coated fibrous mat and the hydrophobic finishform a composite having a thickness of about 0.075 inches (75 mil) orless, more preferably, 0.05 inches (50 mil) or less, most preferably,0.03 (30 mil) inches or less. A preferred lower limit is 0.01 (10 mil)inches.

Preferably, the non-pre-coated mat and hydrophobic finish form acomposite having a density from about 75 to about 115 pcf.

Preferably, the hydrophobic finish of embodiments employing thenon-pre-coated fibrous mat has a weight from about 60 lb/MSF to about160 lb/MSF.

Preferably, the hydrophobic cementitious hydrophobic finish compositionpenetrates at least about 80% into the uncoated glass mat.

The pre-coated glass mat and hydrophobic finish coating will form alayer with negligible penetration of the hydrophobic finish into theglass mat. The thickness of the finished fiber mat composite can be fromabout 0.018 inches to about 0.080 inches (18-80 mil), preferably fromabout 0.025 to about 0.070 inches (25-70 mil), or from about 0.040 toabout 0.060 inches (40-60 mil).

In preferred embodiments with pre-coated glass mat, the hydrophobicfinish composition weight on the pre-coated mat is from about 40lbs./MSF (pounds per thousand square feet) to about 200 lbs./MSF, morepreferably from about 50 lbs./MSF to about 100 lbs./MSF, most preferably61 lbs./MSF to 75 lbs./MSF.

L. Preferred Coating Drying Temperature Versus Drying Time

Preferably, the hydrophobic finish composition sets and dries in about30 to about 60 minutes under conditions of 75° F. and 50% relativehumidity (RH) when used as a coating, particularly during manufacture ofthe cementitious articles of the present invention. Preferably, thehydrophobic finish composition substantially sets and dries in about 30to about 45 minutes at a temperature of about 175° F. Preferably, thehydrophobic finish composition substantially sets and dries in about 3minutes or less at a temperature of about 400° F. These times andtemperatures apply to embodiments with pre-coated fibrous mats andembodiments with non-pre-coated fibrous mats.

Methods of drying the hydrophobic finish coating include but are notlimited to convection oven, infrared oven, and microwave heating.

M. Additional Structural Details

Preferably, the fibrous mat comprises two parts, with one part on eitherside of the core to form a sandwich structure.

Preferably, the hydrophobic finish composition faces both parts of themat.

Preferably, the hydrophobic finish composition comprises,

the film-forming polymer of the finish composition which comprises oneor more of the following polymers: acrylic polymers and copolymers,rubber-based polymers and copolymers such as styrene-butadiene rubber,copolymers of styrene and acrylic, copolymers of vinyl acetate andethylene, copolymers of vinyl chloride and ethylene, copolymers of vinylacetate and VeoVa (vinyl ester of versatic acid), copolymers of vinyllaurate and ethylene, terpolymers of vinyl acetate, ethylene andmethylmethaacrylate, terpolymers of vinyl acetate, ethylene and vinyllaurate, terpolymers of vinyl acetate, ethylene and VeoVa (vinyl esterof versatic acid), and any combination thereof, wherein the film-formingpolymer is in an amount from about 5% to about 25% by weight of the wetfinish,

the silane compound is an alkyl alkoxysilane in an amount equal to fromabout 0.1% to about 5% by weight of the wet finish (water includedbasis),

the extended flow time retention agent comprising either one or morecarboxylic acids, salts of carboxylic acids, or mixtures thereof in anamount from about 0.05 to 1.00 percent by weight on a water free basisof the hydraulic component,

the board passes the test for waterproofness according to ANSI A118.10(revised October 2008), when the board is cast as a ½″ thick board, theboard has a nail pull resistance of at least about 70 pounds inaccordance with ASTM C1178/C1178M-13, or a nail pull resistance of atleast about 80 pounds in accordance with ASTM C1177/C1177M-13 and ASTMC1658/ASTM C1658M-13, when the board is cast as ½″ thick board, theboard has a flexural strength of at least about 80 pounds bearing edgesparallel to the board edge and/or at least about 100 pounds bearingedges perpendicular to the board edge, in accordance with ASTMC1178/C1178M-13, ASTM C1177/C1177M-13 and ASTM C1658/ASTM C1658M-13.

the hydraulic component is in an amount from about 50% to about 85% byweight of the wet hydrophobic finish, and/or

the hydrophobic finish has a pH of at least about 9.

Preferably, the hydrophobic finish composition comprises, consists of,or consists essentially of:

hydraulic component comprising Class C fly ash in an amount from about50 to about 85 percent by weight of the wet finish composition (wetfinish composition means including water),

film-forming polymer in an amount from about 5 to about 25 percent byweight of the wet finish composition,

alkyl alkoxysilane in an amount from about 0.1 to about 5 percent byweight of the wet finish composition,

an extended flow time retention agent comprising either one or morecarboxylic acids, salts of carboxylic acids, or mixtures thereof in anamount from about 0.05 to 1.00 percent by weight based on dry (waterfree) weight of the hydraulic component,

filler in an amount from about 0 to about 50 percent by weight of thefinish composition,

water reducing admixture in an amount from about 0 to about 5 percent byweight of the wet finish composition,

colorant in an amount from about 0 to about 2 percent by weight of thewet finish composition,

other optional additives in an amount from about 0 to about 20 percentby weight of the wet finish composition, and

water in an amount from about 5 to about 30 percent by weight of thefinish composition.

Optional additives include water reducing admixtures, rheologymodifiers, thickeners, gums, air entraining agents, defoamers,reinforcing fibers, colorants, wetting agents, solvents, film formingand coalescing agents, set accelerators, set retarders, preservatives,biocides, bio-polymers, lightweight fillers, hydraulic cements,pozzolans, and inorganic fillers such as calcium carbonate, talc, clays,mica, pozzolanic admixtures, sand, silica, alumina, iron oxide, etc.

In another embodiment, the mat and hydrophobic finish form a compositehaving a thickness from about 0.0075 to about 0.040 inches and a densityfrom about 65 to about 125 pcf (pounds per cubic foot), wherein thefinish has a weight from about 40 to about 200 lb/MSF (pounds perthousand square feet), the hydrophobic finish composition penetrates atleast about 60% into the mat, and the finish has a pH of at least about9. Also, in this embodiment the finish substantially sets and dries inabout 30 to about 60 minutes under conditions of about 75° F. and about50% relative humidity, and the finish substantially sets and dries inabout 30 to about 45 minutes at a temperature of about 175° F. Further,in another embodiment, the finish substantially sets and dries in aboutless than 3 minutes at a temperature of about 400° F.

In a preferred embodiment, the mat and finish form a mat-faced gypsumboard comprising the following:

A gypsum based core,

fibrous mat comprising polymer or mineral fiber, wherein the mat has aninner surface facing at least one face of the gypsum-based core, andhydrophobic finish composition consisting essentially of:

hydraulic component comprising Class C fly ash in an amount from about50% to about 85% by weight of the wet (water included basis) finish, oneor more of the following film-forming polymers: acrylic polymers andcopolymers, rubber-based polymers and copolymers such asstyrene-butadiene rubber, copolymers of styrene and acrylic, copolymersof vinyl acetate and ethylene, copolymers of vinyl chloride andethylene, copolymers of vinyl acetate and VeoVa (vinyl ester of versaticacid), copolymers of vinyl laurate and ethylene, terpolymers of vinylacetate, ethylene and methylmethaacrylate, terpolymers of vinyl acetate,ethylene and vinyl laurate, terpolymers of vinyl acetate, ethylene andVeoVa (vinyl ester of versatic acid), and any combination thereof,

wherein the film-forming polymer is in an amount from about 5% to about25% by weight of the wet finish,

alkyl alkoxysilane in an amount from about 0.1% to about 5% by weight ofthe wet finish,

an extended flow time retention agent comprising either one or morecarboxylic acids, salts of carboxylic acids, or mixtures thereof in anamount from about 0.05 to 1.00 percent by weight of the hydrauliccomponent.

In another embodiment, the mat and finish form a board comprising

(a) gypsum-based core,

(b) fibrous mat comprising polymer or mineral fiber, wherein the mat hasan inner surface facing at least one face of the gypsum-based core, and

(c) hydrophobic finish composition consisting essentially of a hydrauliccomponent comprising Class C fly ash, film-forming polymer, alkylalkoxysilane, and an extended flow time retention agent comprisingeither one or more carboxylic acids, salts of carboxylic acids, ormixtures thereof The hydraulic component comprising Class C fly ash canbe, for example, in an amount from about 50% to about 85% by weight ofthe wet finish composition. The film-forming polymer can be, forexample, in an amount from about 5% to about 25% by weight of the wetfinish composition.

In embodiments in which the hydrophobic finish composition consistsessentially of hydraulic component comprising Class C fly ash,film-forming polymer, and silane compound, and an extended flow timeretention agent comprising either one or more carboxylic acids, salts ofcarboxylic acids, or mixtures thereof, the embodiments preclude theinclusion of any compound other than the aforesaid hydraulic componentcomprising Class C fly ash, film-forming polymer, alkyl alkoxysilane,and an extended flow time retention agent comprising either one or morecarboxylic acids, salts of carboxylic acids, or mixtures thereof, thatmaterially affects the inventive composition (e.g., compounds thatconsiderably hamper the water resistance effect or adversely reducestrength or flowability significantly).

Thus, compounds that would be excluded in a finish compositionconsisting essentially of hydraulic component comprising Class C flyash, film-forming polymer, alkyl alkoxysilane, and an extended flow timeretention agent comprising either one or more carboxylic acids, salts ofcarboxylic acids, or mixtures thereof, would include fillers, aggregate,or calcium carbonate with a mean particle size above 3000 microns;silica, alumina, or iron oxide in a combined amount above 50% by weightof the hydraulic component; Portland cement in an amount above 50% byweight of the hydraulic component; quick lime in an amount above 10% byweight of the hydraulic component; and hydrated lime in an amount above25% by weight of the hydraulic component.

Compounds that would not be excluded in a finish composition consistingessentially of hydraulic component comprising Class C fly ash,film-forming polymer, alkyl alkoxysilane, and an extended flow timeretention agent comprising either one or more carboxylic acids, salts ofcarboxylic acids, or mixtures thereof and compounds that do notmaterially affect the finish composition, such as water, defoamers,fillers such as mica, clays, gums, preservatives, solvents and otheradditives (e.g., binders, alcohols, biocides, colorings), water reducingadmixture additives, as well as other compounds that do not considerablyhamper the water resistance effect or adversely reduce strength orflowability significantly when in a finish composition.

In another embodiment, the mat and finish form a composite having athickness from about 0.0075 to 0.040 inches and a density from about 65to about 125 pcf, wherein the finish has a weight from about 40 to about200 lb/MSF, the finish penetrates at least about 60% into the mat, andthe finish has a pH of at least about 9, and the finish substantiallysets and dries in about 30 to about 60 minutes under conditions of about75° F. and about 50% relative humidity, and the finish substantiallysets and dries in about 30 to about 45 minutes at a temperature of about175° F.

In another embodiment, an article comprises a cementitious core materialand a finish composition facing the cementitious core, wherein thefinish composition comprises Class C fly ash, film-forming polymer,silane compound, wherein the silane is (a) within the general chemicalformula (I):

(R¹O)_(m)—Si—X_(4-m)  (I),

where R¹O is an alkoxy group, X is an organofunctional group, and mranges from 1 to 3 and/or (b) has a molecular weight of at least about150, andan extended flow time retention agent comprising either one or morecarboxylic acids, salts of carboxylic acids, or mixtures thereof,wherein if the silane is a polymer the molecular weight of at leastabout 150 is a weight average molecular weight.

In embodiments employing the pre-coated mat, the mat and finish form acomposite having a thickness from about 0.018 to 0.080 inches (18-80mil) wherein the binder coating is present in an amount of about 40lbs./MSF to about 165 lbs./MSF, wherein the hydrophobic finish has aweight from about 40 to about 200 lbs./MSF, the hydrophobic finishpenetrates a negligible depth into the mat. Also, the finish has a pH ofat least about 9, and the finish substantially sets and dries in about30 to about 60 minutes under conditions of about 75° F. and about 50%relative humidity, and the finish substantially sets and dries in about30 to about 45 minutes at a temperature of about 175° F.

The preceding are merely examples of embodiments. Other exemplaryembodiments are apparent from the entirety of the description herein. Itwill also be understood by one of ordinary skill in the art that each ofthese embodiments may be used in various combinations with the otherembodiments provided herein.

The following examples further illustrate the invention but, of course,should not be construed as in any way limiting its scope.

EXAMPLES

Examples 1-10 are tests on product which are composite product made ofglass-mat faced gypsum baseboard consisting of uncoated glass mat, andfinish coating composition which provides water resistance. The ½ inchgypsum baseboard uses the mold tough formulation at 1600 lb/MSF, and the⅝ inch baseboard uses the formulation for glass-mat interior board at2400 lb/MSF. The finishing coating was made of fly ash that promotestile bond, and acrylic polymer for water resistance. The hydrophobicfinish coating application rate was 110-150 lb/MSF, about ⅓ of which byweight is acrylic polymer. The final product weight is approximately1725 lb/MSF for ½ inch and 2525 lb/MSF for ⅝ inch panel. The productwill be made on a plant specialty line. The hydrophobic finish coatingwas applied as a slurry.

Examples 11-12 are tests on product which are composite product made ofglass-mat faced gypsum baseboard consisting of pre-coated glass mat, andhydrophobic finish coating composition which provides water resistance.

The major components of the hydrophobic finish coating are class C flyash to promote tile bond, and acrylic polymer for water resistance,silane, and extended flow time retention agent. In plant production, thecoating is applied to the glass mat baseboard, and dried in an oven fora few minutes. The drying action drives off the moisture in the polymerso it can form a layer of film. The dried boards are then stacked inunits ready for shipment. Class C fly ash used in the coating hascementitious properties and reacts with water. This reaction, dependingon the reactivity of fly ash, stiffens the mixture and makes itdifficult to work with. Since the curing of coating relies on theremoval of moisture and not the setting of fly ash, this stiffening ofslurry poses a challenge in plant production. Stiffening of coatingslurry leads to buildup on the roller coater and slurry delivery system,which makes extended run difficult. It is preferred the coating staysfluid and workable for at least 30 minutes, or at least 60 minutes,without significant stiffening up.

Citric acid was found adequate in lab environment to control the slurryfor the hydrophobic coating set for a reasonable extended time period.However in industrial scale production at elevated temperatures, citricacid itself was found to have limited effect on controlling stiffeningof the slurry for the hydrophobic coating. There was observed buildup onrollers, which makes it difficult to deliver uniform coating with goodcoverage. The combination of citric acid or sodium citrate with sodiumgluconate was tested at different temperatures, and the mixture hasshown to effectively extend the flow time of the hydrophobic coating anddelay stiffening, even at high hydrophobic coating temperatures.Potassium gluconate, potassium tartrate and sodium tartrate providedextended flow time retention both at ambient and high temperatures.Sodium gluconate can be used alone, or combined with other flow timeretention agents. It has particular advantages when combined with atleast one of citric acid or sodium citrate. Gluconic acid and tartaricacid also provided extended flow time retention both at ambient and hightemperatures. Of the various chemical additives investigated, tartaricacid was found to provide the best flow time retention both at ambientand high temperatures.

Example 1

Three hydrophobic finish coating mixtures were prepared as slurriesusing the formulation listed in TABLE 1-1. Fly ash was sieved through#30 mesh (Standard US mesh size) to remove lumps and grits. Allingredients other than fly ash were mixed together and treated as totalliquids. The fly ash to liquids weight ratio is 2.4 and fly ash topolymer weight ratio is 2.6. PROSIL 9270 silane, aN-Octyltriethoxysilane made by SiVance LLC, was added as 1% by weight offly ash to boost water resistance. AQUABLAK 5968 is a carbon black basedcolorant to give the desired appearance. All three had 0.6% citric acidby weight of fly ash. Mix 2 and 3 had additional 0.25% and 0.5% sodiumgluconate (by weight of fly ash) respectively. Citric acid and sodiumgluconate were added as powder to the polymer and dissolved well beforemixing.

All fly ash and liquids materials were batched and conditioned to 110°F. overnight to achieve a slurry mixture temperature of 110° F. The flyash was slowly poured into the liquids in a bucket, and stirred at fullspeed by a drill mixer. After three minutes of mixing, the mixturetemperature and viscosity were monitored for two hours. Viscosity wasmeasured using a Sheen cup 400 (see FIG. 4). A Sheen cup is similar to aFord cup, but with a bigger opening to allow for testing of more viscousmaterials. The Sheen cup 400 used was model 401/6, BS 3900, A6-1971,with an opening of 7.14 mm. The cup orifice was sealed, usually with afinger, while the coating was filled flush with the top. The finger sealwas then removed and stopwatch was started simultaneously. The time wasstopped at the first break in flow. This elapsed time represents the‘flow-time’ of the test, or viscosity of the coating mixture. Viscosityusually increases with coating setting.

TABLE 1-1 Formulation for 2-gallon hydrophobic finish coating mixes inExample 1 (amounts in grams) Mix 2 Mix 3 0.6% citric 0.6% citric Mix 1acid acid 0.6% 0.25% sodium 0.5% sodium citric acid gluconate gluconateScherer C fly ash 7962 7962 7962 (−30 mesh) (g) Liquid polymer FORTON3016 3016 3016 VF 774 (g) available from EPS Inc., Marengo, Illinois***AQUABLAK 5968 (g) 36 36 36 (aqueous carbon black dispersion availablefrom Chromascape Inc., Ohio) PROSIL 9270 (g) available 114 114 114 fromSiVance LLC, Gainesville FL* Citric acid (g)** 48 48 48 Sodium gluconate(g) — 20 40 *PROSIL 9270 is 70% active solids, hence, 114*0.70/7962*100= 1.0%. **Citric Acid - 48/7962*100 = 0.60% ***FORTON VF 774 is about 51wt. % polymer solids %

The initial temperature after mixing of the slurry for the hydrophobiccoating was close to 110° F. for all three mixes. The slurry mixture waskept at 70° F. afterwards. The purpose was to simulate plant productionat ambient temperature of about 70° F., whereas the initial slurrytemperature can be elevated due to close proximity of raw materials toheat sources. The initial Sheen cup flow time reading for Mix 1 withcitric acid only was close to 40 seconds (shown in FIG. 4), which isvery thick for roller coater application. Mix 2 and 3, with sodiumgluconate, had much lower initial Sheen cup flow time reading of 26seconds. Not only the high initial Sheen cup flow time reading, Mix 1also showed significantly faster stiffening, reaching 60 seconds after20 minutes, and 120 seconds after 30 minutes. The hydrophobic coatingslurry was hardly flowable 30 minutes after mixing. By contrast, mix 2and 3 demonstrated Sheen cup flow time reading of under 40 seconds after50 minutes, and under 60 seconds after 2 hours. The behavior of mix 2and 3 is highly desirable at the plant, which minimizes the formation oflumps and buildup due to fly ash reaction, even at elevated temperature.The dosage of sodium gluconate was found to be not significant. Thisexample showed that the combination of citric acid and sodium gluconateis acts as a very powerful flow time retention agent to slow down thestiffening of mixtures containing class C fly ash, even at hightemperatures.

Example 2

Two hydrophobic finish mixtures were prepared to compare the viscositydevelopment over time when the liquids are chilled from elevatedtemperature to room temperature. The formulations prepared as slurriesare very similar to those in Example 1, except 0.3% citric acid and 0.3%sodium gluconate were used, see TABLE 2-1 for details. The fly ash washeated up to 110° F. Citric acid and sodium gluconate were added aspowder to the polymer. The liquids were conditioned to 90° F. overnight,and then rapidly chilled to 70° F. in about 15 minutes by ice water, tosimulate plant production when rapid chilling is used to control coatingopen time. The chilled liquids were mixed with the fly ash to formcoating mixture. The purpose of this test is to simulate coatingstiffening at the plant when chiller is used to cool down the liquids.

TABLE 2-1 Formulation for 2-gallon hydrophobic finish coating mixes inExample 2 (amounts in grams) Mix 2 Mix 1 0.3% citric acid 0.3% 0.3%sodium citric acid gluconate Scherer C fly ash 7962 7962 (−30 mesh) (g)Liquid polymer FORTON 3016 3016 VF 774 (g) available from EPS Inc.,Marengo, IL AQUABLAK 5968 (g) 36 36 (aqueous carbon black dispersionavailable from Chromascape Inc., OH PROSIL 9270 (g) available from 114114 SiVance LLC, Gainesville, FL Citric acid (g) 24 24 Sodium gluconate(g) — 24

The initial temperature of thew slurry for the hydrophobic coating wasabout 90° F., and the initial Sheen cup flow time reading was around 20seconds for both mixes (see FIG. 6). Mix 2 (0.3% citric acid and 0.3%sodium gluconate) had similar stiffening behavior as Mix 1 (0.3% citricacid only) up to 50 minutes, except for the higher 40-minute readingwhich was probably due to coating skin over on the surface due toevaporation. After 50 minutes, Mix 2 containing 0.3% citric acid and0.3% sodium gluconate exhibited obvious advantage with Sheen cup flowtime reading under 50 seconds after 2 hours. By comparison, Mix 1containing 0.3% citric acid only showed significant stiffening reachingSheen cup flow time reading of 85 seconds after 2 hours.

Example 3

Six hydrophobic finish coating mixtures were prepared as slurries usingthe formulations shown in TABLE 3-1. These are small batches being about10% of the quantity in Example 1 & 2. Mixes 1-3 were based on fly ash(FA) and water, with the water content the same as that in polymerVF774. For example, for a fly ash content of 796 g, 151 g water ispresent for a polymer content of 302 g (the polymer is 50% solidcontent). This calculation is based on the assumption that the reactionbetween fly ash and water is responsible for the stiffening of coating.Mix 1 was a mixture of fly ash (FA) and water; Mix 2 had 0.3% citricacid; Mix 3 had 0.3% citric acid and 0.3% sodium gluconate. Mixes 4-6were based on fly ash and VF774 polymer; Mix 5 had 0.3% citric acid; Mix6 had 0.3% citric acid and 0.3% sodium gluconate. The fly ash to polymerratio was the same as in Example 1 and 2. Citric acid and sodiumgluconate were pre-dissolved in 10 grams of water. The solution wasadded to the mixing water, followed by hand mixing with the fly ash. Allraw materials were kept at room temperature prior to mixing.

After mixing, the slurry (˜280 g) was placed in a 6 ounces Styrofoam cupand placed in an insulated STYROFOAM box. The temperature response wasmeasured continuously using a computerized data collection program. Themaximum temperature and time to maximum temperature were used asindications of the reactivity of the experimental mixtures.

TABLE 3-1 Formulation for hydrophobic finish coating mixes in Example 3Mix 3 Mix 6 Mix 2 FA + water; Mix 5 FA + polymer; Mix 1 FA + water; 0.3%citric acid; Mix 4 FA + polymer; 0.3% citric acid; FA + water 0.3%citric acid 0.3% sodium gluconate FA + polymer 0.3% citric acid 0.3%sodium gluconate Scherer C fly ash 796 796 796 796 796 796 (−30 mesh)(g) Mixing water (g) 151 151 151 Liquid polymer 302 302 302 FORTON VF774 (g) available from EPS Inc., Marengo, Illinois Citric acid (g) — 2.42.4 — 2.4 2.4 Sodium gluconate (g) — 2.4 — — 2.4 Water for citric acid,— 10 10 — 10 10 sodium gluconate solution (g)

The temperature rise data are shown in FIG. 7(a) for fly ash and watermixes, and FIG. 7(b) for fly ash and polymer mixes. For Mix 1 containingfly ash and water only, the initial mix was very thick due to the lowwater-to-fly ash ratio of 0.19. After 80 minutes, the temperature peakedat 108° F., showing significant fly ash reaction. The mix was hard andnot deformable after 25 minutes. When 0.3% citric acid was added (Mix2), peak temperature occurrence was drastically delayed to 54 hours, andpeaked at 88° F. Mix 2 hardened in a few hours. When both citric acidand sodium gluconate were used (Mix 3), there was almost no peak intemperature rise data, and the mix was still squeezable the next day.This data demonstrate that the combination of citric acid and sodiumgluconate is extremely powerful in achieving extended flow timeretention and delaying the stiffening of slurry.

FIG. 7(b) for mixes 4-6 shows similar trend for fly ash and polymermixtures. Mixes 4-6 correspond to Mixes 1-3, except polymer was usedinstead of water. Mix 4 containing fly ash and polymer peaked at 95° F.after 65 minutes, and the mix hardened within one hour. With 0.3% citricacid (mix 5), peak temperature occurred at 85° F. after 60 hours. ForMix 6 containing both citric acid and sodium gluconate, no temperaturepeak was obvious for 80 hours.

Example 4

This example is similar to Example 3, except sodium citrate was used toreplace citric acid. Sodium citrate has the benefit of being pH neutral,and will not change the pH of the latex film forming polymer. Most latexprefers pH close to 7 or slightly alkaline environment, with low pHcausing instability. The particular polymer VF 774 has a pH of 8-10.When mixed with citric acid, the pH goes down to 3.15, which could be aconcern if the liquids stay in a tank for extended time. The formulationis shown in TABLE 4-1. Same as in Example 3, sodium citrate and sodiumgluconate were pre-dissolved before blended with the polymer. All rawmaterials were kept at room temperature.

TABLE 4-1 Formulation for mix in Example 4 (amounts in grams) Mix 3 Mix6 Mix 2 FA + water; Mix 5 FA + polymer; Mix 1 FA + water; 0.3% sodiumcitrate; Mix 4 FA + polymer; 0.3% sodium citrate; FA + water 0.3% sodiumcitrate 0.3% sodium gluconate FA + polymer 0.3% sodium citrate 0.3%sodium gluconate Scherer C fly ash 796 796 796 796 796 796 (−30 mesh)(g) Mixing water (g) 151 151 151 Liquid polymer 302 302 302 FORTON VF774 (g) available from EPS Inc., Marengo, Illinois Citric acid (g) — 2.42.4 — 2.4 2.4 Sodium gluconate (g) — 2.4 — 2.4 Water for citric acid, —10 10 — 10 10 sodium gluconate solution (g)

The temperature rise data are shown in FIG. 8 for fly ash and watermixes, and FIG. 9 for fly ash and polymer mixes. For Mix 1, thetemperature peaked at 108° F. after 80 minutes, showing significant flyash reaction. The mix was hard and not deformable after 25 minutes. When0.3% sodium citrate was added (Mix 2), peak temperature occurrence wasdelayed to 13.5 hours, and peaked at 115° F. Comparing with Mix 2 inExample 3 where citric acid was used, it seems that citric acid is morepowerful than sodium citrate. When both sodium citrate and sodiumgluconate were used (Mix 3), there was almost no peak in temperaturerise data, and the mix was still squeezable the next day. This datademonstrate the combination of sodium citrate and sodium gluconate isalso extremely powerful in achieving extended flow time retention anddelaying the stiffening of slurry.

FIG. 9 for mixes 4-6 shows similar trend for fly ash and polymer mixes.Mixes 4-6 correspond to mixes 1-3, except that polymer was used. Mix 5was very interesting showing double peaks. The first one appeared 8.6hours after mixing at 87° F., and the second peak occurred after 44hours at 95° F. For Mix 6 containing both sodium citrate and sodiumgluconate, no temperature peak was obvious for 80 hours.

Example 5

An industrial scale plant trial tested a combination including 0.3%sodium citrate and 0.3% sodium gluconate. The formulation is shown inTABLE 5-1 for a liquids batch of approximately 75 gallons. Theproportions of each material were the same as in the Examples 3 and 4.The polymer VF774 was first pumped into the mixing tank, followed byPROSIL 9270. Sodium citrate and sodium gluconate was each made into 25%solution. The two solutions as well as the colorant were put into themixing tank and then blended by agitator. The blended liquids was thenpumped to the liquids metering tank, and fed into the mixer. Fly ash wasfed into the mixer by screw conveyer.

The mixed hydrophobic finish coating slurry was transferred to a coneshape plastic hopper, and pumped to the roller coater. The applicationrate of hydrophobic finish coating was around 110 lb/MSF. The ambienttemperature was around 78° F. at the time of trial. Fresh hydrophobiccoating slurry samples were collected before the feed to the pump forviscosity and temperature measurements. During the three-hour trial,Sheen cup flow time readings stayed stable at around 11 seconds, andcoating temperature ranged between 78° F. and 83° F. There was nobuildup inside the pump or on the roller coater after the three hourtrial. A coating sample was kept overnight for observation, which wasstill fluid except for a skin on the surface the next day. This trialverified the efficacy of the flow time retention agents at plantproduction environment.

TABLE 5-1 Hydrophobic finish coating formulation for Plant Trial 0.3%sodium citrate 0.3% sodium gluconate Scherer C fly ash 1588 (−30 mesh)(lbs) Liquid polymer FORTON 586.7 VF 774 (lbs) available from EPS Inc.,Marengo, Illinois AQUABLAK 5968 (lbs) 7.1 (aqueous carbon blackdispersion available from Chromascape Inc., Ohio) PROSIL 9270 (lbs) 22.7available from SiVance LLC, Gainesville, FL Sodium citrate (lbs) 4.8Sodium gluconate (lbs) 4.8 Water for sodium citrate, 38.4 sodiumgluconate solution (lbs)

The waterproofness of the coated panels of Example 5 was determined inaccordance to the ANSI A118.10 standard. The waterproofness test methodwas modified to make it more aggressive by having a 48″ tall watercolumn instead of 24″ as prescribed in the ANSI A118.10 standard. Thetest was initiated and drop in water level in the column was measured asa function of time. After the passage of 48-hours, no change in waterlevel (i.e., 0″ drop in water level) was noted thus indicating a highdegree of waterproofness of the hydrophobic finish coating and coatedpanels of this invention.

Example 6

Three hydrophobic finish coating mixtures were prepared using theformulation listed in TABLE 6-1. Fly ash was sieved through #30 mesh toremove lumps and grits. All ingredients other than fly ash were mixedtogether and treated as total liquids. The fly ash to liquids weightratio is 2.0 and fly ash to polymer weight ratio is 2.1. PROSIL 9270(70% active ingredient) a silane to boost water resistance, was added as1% by weight of fly ash. AQUABLAK 5968 is a carbon black based colorantto give the desired appearance. Different carboxylic acids were used at0.3% by weight of fly ash, added as 50% by weight aqueous solution, andblended with other liquids before mixing.

All fly ash and liquids materials were conditioned to 110° F. overnightto achieve a slurry temperature of 110° F. This experiment was used toidentify the best chemical additive during summer time, when slurrytemperature will be consistently high and extending slurry open time isextremely challenging. The fly ash was slowly poured into the liquids ina bucket, and stirred at full speed by a drill mixer. After threeminutes of mixing, the slurry was kept at 110° F. oven and viscosity wasmonitored until the slurry became so viscous that the viscosity couldnot be measured by Sheen cup flow time.

TABLE 6-1 Formulations for 2-gallon hydrophobic finish coating mixes inExample 6 (amounts in grams) Mix 1 - 0.3% Mix 2- 0.3% Mix 3 - 0.3%citric acid tartaric acid gluconic acid Scherer C fly ash 7962 7962 7962(−30 mesh) (g) Liquid polymer 3791 3791 3791 FORTON VF 774 (g) availablefrom EPS Inc., Marengo, IL AQUABLAK 5968 (g) 36 36 36 (aqueous carbonblack dispersion available from Chromascape Inc., Ohio) PROSIL 9270 (g)114 114 114 available from SiVance LLC, Gainesville, FL Citric acid (g)24 — — Tartaric acid (g) — 24 — Gluconic acid (g) — — 24

The Sheen cup flow time readings (seconds) over time after mixing(minutes) are plotted in FIG. 10. The initial Sheen cup flow timereadings for all three mixes were similar around 15 seconds. The mixturecontaining 0.3% gluconic acid (Mix 3) stiffened fast, and turned tothick pastes after 5-6 hours. The mixture containing 0.3% citric acid(Mix 1) showed over 60 seconds Sheen cup flow time at 5 hours, which isthick and difficult to process using industrial manufacturing processes.Mix with tartaric acid exhibited the best flow time retentionperformance (Mix 2), with the coating measuring 30 seconds Sheen cupflow time after 24 hours of mixing, and 92 seconds Sheen cup flow timeafter 6 days in 110° F. oven (not plotted here).

Surface water absorption test, also commonly called Cobb test, wasconducted in accordance with ASTM C473 Physical Testing of Gypsum PanelProducts. The specification is water absorption of not more than 1.6grams after 2 hours of elapsed time in accordance with ASTM C1658 GlassMat Gypsum Panels Sec. 7 Glass Mat Water-Resistant Gypsum Panel, and notmore than 0.5 g after 2 hours of elapsed time in accordance with ASTMC1178 Coated Glass Mat Water-Resistant Gypsum Backing Panel. The testevaluates the water-repellent surfaces by damming a specific area on thetreated surface, filling that area with water for 2 hours, and measuringthe weight gain after test. The specific area exposed to water isdefined by a Cobb ring of enclosed area of 15.5 in² (100 cm²) and 1 intall (2.54 cm). The test specimens are 6 in. (15.2 cm) square and beforeinitiating the test they are conditioned in 70±5° F. (21±2° C.) and50±2% relative humidity atmosphere until constant weight is attainedwithin 0.1%.

The samples used for surface water absorption test were prepared in thelab by manually coating glass-mat gypsum baseboard. The tool used isknown as the “Magic Trowel” (by TexMaster Tools), similar to a squeegee.The desired amount of hydrophobic finish coating at 125 lb/msf wasapplied uniformly on the board and air dried subsequently. TABLE 6-2shows the surface water absorption results.

TABLE 6-2 Surface water absorption as a function of carboxylic acid typeMix 1 - 0.3% Mix 2 - 0.3% Mix 3 - 0.3% citric acid tartaric acidgluconic acid Surface water 0.19 0.24 0.37 absorption (grams)

There is a significant difference in water absorption performance amongsamples containing different carboxylic acids, even though all met theless than 0.5 gram specification in accordance with ASTM C1178, and lessthan 1.6 grams specification in accordance with ASTM C1658 Sec. 7. Thecoating slurry containing 0.3% citric acid showed the best performanceof 0.19 gram (Mix 1), which was half of the coating slurry containedgluconic acid (Mix 3). The samples containing tartaric acid provided0.24 gram water absorption (Mix 2). Combining this with the viscositymeasurement, tartaric acid demonstrated the best overall performance,followed by citric acid.

The waterproofness of the coated panels of Example 6 was determined inaccordance to the ANSI A118.10 standard. The waterproofness test methodwas modified to make it more aggressive by having a 48″ tall watercolumn instead of 24″ as prescribed in the ANSI A118.10 standard. Thetest was initiated and drop in water level in the column was measured asa function of time. After the passage of 48-hours, no change in waterlevel (i.e., 0″ drop in water level) was noted thus indicating a highdegree of waterproofness of the hydrophobic finish coating and coatedpanels of this invention.

Example 7

The procedure of Example 6 was repeated with three hydrophobic finishcoating mixtures prepared using the formulation listed in TABLE 7-1.Different sodium salts of carboxylic acids were used at 0.3% by weightof fly ash, added as 50% by weight aqueous solution and blended withother liquids before mixing.

TABLE 7-1 Formulations for 2-gallon hydrophobic finish coating mixes inExample 7 (amounts in grams) Mix 2 - 0.3% Mix 1 - 0.3% sodium Mix 3 -0.3% sodium citrate gluconate sodium tartrate Scherer C fly ash 79627962 7962 (−30 mesh) (g) Liquid polymer 3791 3791 3791 FORTON VF 774 (g)available from EPS Inc., Marengo, Illinois AQUABLAK 5968 (g) 36 36 36(aqueous carbon black dispersion available from Chromascape Inc., Ohio)PROSIL 9270 (g) 114 114 114 available from SiVance LLC, Gainesville, FLSodium citrate (g) 24 — — Sodium gluconate (g) — 24 — Sodium tartrate(g) — — 24

The Sheen cup flow time readings are plotted in FIG. 11. Mix 1containing sodium citrate showed the weakest effect on flow timeretention, with the mixture gelling up after 5 hours of mixing and notas effective as citric acid shown in the previous sample. Mix 2containing 0.3% sodium gluconate showed very slow stiffening up to 4hours, followed by significant increase in viscosity, reaching 35seconds flow time at 6 hours. After that the coating slurry got so thickthat Sheen cup flow time could not be measured. Mix 3 containing sodiumtartrate demonstrated the best flow time retention performance among thethree, with the coating slurry coating being very fluid at about 20seconds flow time after 7 hours. After that some big spheres started toappear in the sample, an indication of some reactions occurring in thematerial and potential buildup issues in a continuous commercialmanufacturing process. Sodium tartrate also showed a weaker flow timeretention performance than tartaric acid.

The samples used for surface water absorption test were prepared in thelab by manually coating glass-mat gypsum baseboard using “Magic Trowel”(by TexMaster Tools). The desired amount of hydrophobic finish coatingof 125 lb/msf was applied uniformly on the board and air driedsubsequently. TABLE 7-2 shows surface water absorption results, with allresults between 0.30-0.40 grams.

TABLE 7-2 Surface water absorption as a function of carboxylic acid salttype Mix 2 - 0.3% Mix 1 - 0.3% sodium Mix 3 - 0.3% sodium citrategluconate sodium tartrate Surface water 0.39 0.31 0.34 absorption(grams)

Each sodium salt of carboxylic acid showed a higher water absorptionthan its acid counterpart. It is desirable to have as low waterabsorption as possible so that there is sufficient margin to failure,considering the potential variations occurring in industrial productionprocesses.

Example 8

The procedure of Example 6 was repeated with three hydrophobic finishcoating mixtures prepared as slurries using the formulation listed inTABLE 8-1. Different potassium salts of carboxylic acids were used at0.3% by weight of fly ash, added as 50% by weight aqueous solution andblended with other liquids before mixing.

TABLE 8-1 Formulations for 2-gallon hydrophobic finish coating mixes inExample 8 (amounts in grams) Mix 1 - 0.3% Mix 2 - 0.3% Mix 3 - 0.3%potassium potassium potassium citrate gluconate tartrate Scherer C flyash 7962 7962 7962 (−30 mesh) (g) Liquid polymer 3791 3791 3791 FORTONVF 774 (g) available from EPS Inc., Marengo, Illinois AQUABLAK 5968 (g)36 36 36 (aqueous carbon black dispersion available from ChromascapeInc., Ohio) PROSIL 9270 (g) 114 114 114 available from SiVance LLC,Gainesville, FL Potassium 24 — — citrate (g) Potassium — 24 — gluconate(g) Potassium — — 24 tartrate (g)

The Sheen cup flow time readings are shown in FIG. 12 Mix 1 containingpotassium citrate performed very similarly to sodium citrate and gelledafter 3 hours. Mix 2 containing potassium gluconate also mirrored itssodium counterpart, with the mixture showing slow stiffening up to 6hours, and rapid thickening afterwards. Mix 3 containing potassiumtartrate performed the best in this group, and better than sodiumtartrate, with the coating measuring 32 seconds Sheen cup flow timeafter 24 hours (not plotted here)

The samples used for surface water absorption test were prepared in thelab by manually coating glass-mat gypsum baseboard using “Magic Trowel”(by TexMaster Tools). The desired amount of hydrophobic finish coatingof 125 lb/msf was applied uniformly on the board and air driedsubsequently. TABLE 8-2 shows surface water absorption results verysimilar to the sodium salts of the same carboxylic acid, with all threemixtures between 0.30-0.40 grams.

TABLE 8-2 Surface water absorption as a function of carboxylic acid salttype Mix 1 - 0.3% Mix 2 - 0.3% Mix 3 - 0.3% potassium potassiumpotassium citrate gluconate tartrate Surface water 0.36 0.32 0.37absorption (grams)

Example 9

The procedure of Example 6 was repeated with four hydrophobic finishcoating mixtures prepared using the formulation listed in TABLE 9-1.However, combinations of two salts of carboxylic acids or a combinationof a carboxylic acid and a salt of carboxylic acid were used in eachmixture. These carboxylic acid-based chemical additives were preparedinto a 25% by weight aqueous solution and the prepared solution wasblended with other liquids before mixing with the fly ash.

TABLE 9-1 Formulations for 2-gallon hydrophobic finish coating mixes inExample 9 Mix 1 Mix 2 Mix 3 Mix 4 0.3% sodium citrate + 0.3% potassiumcitrate + 0.3% citric acid + 0.3% citric acid + 0.3% sodium gluconate0.3% potassium gluconate 0.3% sodium gluconate 0.15% potassium tartrateScherer C fly ash (−30 mesh) (g) 7962 7962 7962 7962 Liquid polymerFORTON VF 774 (g) 3791 3791 3791 3791 available from EPS Inc., Marengo,Illinois AQUABLAK 5968 (g) (aqueous carbon 36 36 36 36 black dispersionavailable from Chromascape Inc., Ohio) PROSIL 9270 (g) available fromSiVance 114 114 114 114 LLC, Gainesville, FL Sodium citrate (g) 24 — — —Sodium gluconate (g) 24 — 24 — Potassium citrate (g) — 24 — — Potassiumgluconate (g) — 24 — — Citric acid (g) — — 24 24 Potassium tartrate (g)— — — 12

FIG. 13 shows the Sheen cup flow time readings. Mix 1 (0.3% sodiumcitrate+0.3% sodium gluconate) showed slightly improved open timecompared to each individual component, measuring 22 seconds Sheen cupflow time after 7 hours. Mix 2 (0.3% potassium citrate+0.3% potassiumgluconate) is not shown. Mix 3 (0.3% citric acid+0.3% sodium gluconate)showed extremely extended open time of 25 seconds after 27 hours. Thisis significantly improved over each individual component, showingsynergy between the two chemical additives. Mix 4 (0.3% citricacid+0.15% potassium tartrate) showed improved open time compared toeach individual component.

TABLE 9-2 shows the surface water absorption results at a hydrophobicfinish coating level of 125 lbs./MSF

TABLE 9-2 Mix 1 - 0.3% Mix 2 - 0.3% Mix 3 - 0.3% Mix 4 - 0.3% sodiumcitrate + potassium citrate + citric acid + citric acid + 0.3% sodiumgluconate 0.3% potassium gluconate 0.3% sodium gluconate 0.15% potassiumtartrate Surface water absorption (grams) 0.55 0.56 0.44 0.45 as afunction of mixtures of carboxylic acid based chemical additives

The two mixtures (mixes 1 & 2) containing two salts of carboxylic acidsmet the less than 1.6 grams specification in accordance with ASTM C1658Sec. 7, but did not meet the less than 0.5 gram specification per ASTMC1178. The two mixtures containing the combination of a carboxylic acidand a salt of carboxylic acid (mixes 3 and 4) passed marginally. Thisdemonstrates combinations of the shown chemical additives are relativelyless desirable for products needing to comply with ASTM C1178.

Example 10

The procedure of Example 6 was repeated with two hydrophobic finishcoating mixtures prepared using the formulation listed in TABLE 10-1.Mix 1 had tartaric acid at 0.3% by weight of fly ash, with tartaric acidadded as 50% by weight aqueous solution, and blended with other liquidsbefore mixing. Mix 2 had an additional polycarboxylate ether basedsuperplasticizer at 1% by weight of fly ash. The superplasticizer usedwas SIKA VISCOCRETE G2 with 40% solid content. The objective of thisinvestigation was to determine the effect of polycarboxylate ethersuperplasticizer, a chemical derived from carboxylic acid family, onslurry viscosity and flow time.

All fly ash and liquids materials were at room temperature of about 70°F. The fly ash was slowly poured into the liquids in a bucket, andstirred at full speed by a drill mixer. After three minutes of mixing,the slurry was kept at 70° F., and viscosity was measured by Sheen cupflow time. TABLE 10-1 shows formulations for 2-gallon mix in Example 10.

TABLE 10-1 Formulations for 2-gallon hydrophobic coating mixes inExample 10 (amounts in grams) Mix 2 Mix 1 0.2% tartaric acid, 0.2%tartaric acid 1% superplasticizer Scherer C fly ash 7962 7962 (−30 mesh)(g) Liquid polymer FORTON 3791 3791 VF 774 (g) available from EPS Inc.,Marengo, Illinois AQUABLAK 5968 (g) 36 36 (aqueous carbon blackdispersion available from Chromascape Inc., Ohio) PROSIL 9270 (g)available 114 114 from SiVance LLC, Gainesville, FL Tartaric acid (g) 1616 Sika VISCOCRETE G2 (g) — 200

The Sheen cup flow time for mix 1 was measured at 11 seconds aftercompletion of mixing. Surprisingly, the Sheen cup flow time for mix 2was measured at 40 seconds. This result was unexpected sincepolycarboxylate ether based superplasticizers are known in the art(Portland cement and concrete industry) for action on reducing viscosityand imparting superior flow to cement slurry mixtures. This resultdemonstrates not all chemicals derived from carboxylic acid family workin a similar fashion as the preferred carboxylic acids and salts ofcarboxylic acids of this invention.

All references, including publications, ASTM and ANSI standards, patentapplications, and patents, cited herein are hereby incorporated byreference to the same extent as if each reference were individually andspecifically indicated to be incorporated by reference and were setforth in its entirety herein.

The use of the terms “a” and “an” and “the” and “at least one” andsimilar referents in the context of describing the invention (especiallyin the context of the following claims) are to be construed to coverboth the singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The use of the term “at least one”followed by a list of one or more items (for example, “at least one of Aand B”) is to be construed to mean one item selected from the listeditems (A or B) or any combination of two or more of the listed items (Aand B), unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Example 11

This example uses pre-coated glass mat on one surface of the board. Thepre-coated glass mat is 24-26 mil thick, compared to 17-19 mil for theuncoated glass mat in Examples 1-10. For the pre-coated glass mat, theweight of the glass mat prior to applying the binder coating is about 25lbs./MSF, and the acrylic based coating weight (dry basis, in otherwords a water free basis) is 65 lbs./MSF, totaling 90 lbs./MSF for thepre-coated glass mat. The acrylic based coating is only on the faceside, with no coating on the side facing gypsum core.

⅝″ glass mat sheathing panel consisting of pre-coated glass mat was usedas the baseboard in the evaluation. The ⅝″ glass mat sheathing panel washand coated in the lab using MAGIC TROWEL squeegee. With the pre-coatedglass mat, this example tests whether lower than 120 lbs./MSFhydrophobic finish coating weight is sufficient to achieve the desiredperformance. Three levels of hydrophobic finish coating weights wereused, 50, 75, and 100 lbs./MSF. The hydrophobic finish coatingformulation is shown in TABLE 11-1.

TABLE 11-1 Hydrophobic finish coating formulation Ingredient* wt (%)Batch weight (g) SCHERER C Fly Ash (−30 mesh) 66.35 600 Liquid polymerFORTON VF 774, available 32.52 271 from EPS Inc., Marengo, IllinoisAQUABLAK 6958 colorant (aqueous carbon 0.66 2.7 black dispersionavailable from Chromascape Inc., Ohio) PROSIL 9270 silane (70% active)available 0.66 8.6 from SiVance LLC, Gainesville, FL Gluconic acid (50%solution) 3.6 Total 100.19 886 *On a dry (water free) basis, fly ash is80%, polymer solids 18%, PROSIL 0.8%, gluconic acid 0.2% (for thisexample). On a wet basis, fly ash 67-71% FORTON VF 774 polymer 27-31%(which is 13.5-15.5% polymer solids), PROSIL0.9-1%, colorant 0.3%,retarder 0.4% (percent ranges encompassing all the examples).

The hydrophobic finish coating was manually applied to the surface ofthe board, and air dried before testing. The samples were tested forsurface water absorption (Cobb test), water penetration, and tile bond.

For surface water absorption (Cobb test), the sheathing panel (withpre-coated glass mat, and no hydrophobic finish coating) was alsoincluded as reference. The results are shown in FIG. 16. It is observedthat the sheathing panel without any additional coating shows reasonablygood Cobb result of 0.59 gram. The specification for glass mat tilebacker is less than 0.5 gram in accordance with ASTM C1178, and forglass mat water-resistant panel is less than 1.6 gram in accordance withASTM C1658 Sec. 7. When hydrophobic finish coating is applied, thepanels showed similar Cobb results of about 0.36 gram at the threecoating levels. It seems hydrophobic finish coating weight of more than50 lbs./MSF does not further improve the Cobb result.

Water column test was performed on the coated samples, as well as glassmat roof board, and glass mat sheathing panel. Glass mat roof board hasuncoated glass mat as in Examples 1-10, and glass mat sheathing panelhas pre-coated glass mat with no additional coating was applied on thepanels. In the test, a 48 in high water head is applied on the topsurface of specimens, and water level drop is measured after 48 hours asan indication of water resistance. The results after 48 hours aresummarized in Table 11-2.

Glass mat roof board had all water leaked out after 48 hours, which isnot unusual with uncoated glass mat. With pre-coated glass mat on thesurface, glass mat sheathing panel showed better performance than roofboard, with 12.06 inch and 20.75 inch water level drop for the twospecimens. All glass mat sheathing panels with hydrophobic finishcoating had zero water level drop, even at 50 lbs./MSF. This is veryencouraging as it indicates the potential to significantly lowerhydrophobic finish coating weight.

TABLE 11-2 Water level drops for different panels Spec- Spec- imen 1imen 2 Glass mat roof board (with uncoated glass mat) 48.0 Glass matsheathing panel (with pre-coated glass mat) 12.06 20.75 Glass matsheathing panel 50 lbs./MSF 0 0 (with pre-coated glass mat) 70 lbs./MSF0 0 and hydrophobic finish coating 100 lbs./MSF  0 0

Tile bond was tested for glass mat sheathing panel (with pre-coatedglass mat), coated with hydrophobic finish coating. With the pre-coatedglass mat, there was a concern of weak bond between the pre-coated glassmat and hydrophobic finish coating due to lack of physical bond betweenthe two. If that became the weakest link, the assembly would fail at theinterface of the pre-coated glass mat and hydrophobic finish coating.

MAPEI modified thinset ceramic tile mortar (available from MAPEICorporation, Florida) was used to attach the tiles to the substrate. Theassemblies were tested after 7 days of curing at room temperature. FIG.17 shows data for tile bond results for Example 11. In particular, thecoated panels demonstrated 130-160 psi tile bond, significantly higherthan the minimum 50 psi requirement. More importantly, the failure modewas between the pre-coated glass mat and gypsum core, indicatingexcellent bond between the pre-coated glass mat and hydrophobic finishcoating.

The optical images of the uncoated and pre-coated glass mat are shown inFIG. 18(a), (b), respectively. FIG. 18(a) shows optical images of glassmat, 20× uncoated. The uncoated glass mat in FIG. 18(a) is the same asthe one used for glass mat roof board, and in Examples 1-10 individualfilaments can be seen with a lot of voids among them. FIG. 18(b) showsoptical images of glass mat, 20× pre-coated. For the pre-coated glassmat (shown in FIG. 18(b)), only the surface filaments are seen with mostvoids covered by the coating.

FIGS. 19(a), (b) shows the cross-section of the hand coated samplesconsisting of pre-coated glass examined using optical microscope. Inparticular, FIG. 19(a) shows the cross section of hand coated samples,50× for 50 lbs./MSF hydrophobic finish coating. FIG. 19(b) shows thecross section of hand coated samples, 50× for 100 lbs./MSF hydrophobicfinish coating. With the pre-coated glass mat, the hydrophobic finishcoating penetration into the pre-coated glass mat is negligible. It isseen that gypsum slurry penetrates all the way into the uncoated side ofglass mat, and meets the green coating. Gypsum slurry penetration depthinto the raw glass fiber side is 11-22 mil.

Example 12

In this example, the hydrophobic finish coating was prepared withoutsilane and applied to ⅝″ glass mat sheathing panel (with pre-coatedglass mat) using a MAGIC TROWEL squeegee. Two levels of hydrophobicfinish coating weights were used, 50 and 75 lbs./MSF. The formulation isshown in the TABLE 12-1. The samples were tested for surface waterabsorption (Cobb test).

TABLE 12-1 Hydrophobic finish coating formulation Ingredient wt (%)Batch weight (g) SCHERER C Fly Ash (−30 mesh) 66.35 600 Liquid polymerFORTON VF 774, 32.52 271 available from EPS Inc., Marengo, IllinoisAQUABLAK 6958 colorant (aqueous 0.66 2.7 carbon black dispersionavailable from Chromascape Inc., Ohio) Gluconic acid (50% solution) 3.6Total 100.19 877

For surface water absorption (Cobb test), the sheathing panel (withpre-coated glass mat, and no hydrophobic finish coating) was alsoincluded as reference. The surface water absorption (Cobb test) resultsare shown in FIG. 20. FIG. 20 shows the sheathing panel without anyadditional coating shows reasonably good Cobb result of 0.59 gram. Thespecification for glass mat tile backer is less than 0.5 gram inaccordance with ASTM C1178, and for glass mat water-resistant panel isless than 1.6 gram in accordance with ASTM C1658. When hydrophobicfinish coating without silane is applied, the panels showed similar Cobbresults of about 0.33 gram at the two coating levels. These results aresimilar to those in Example 11 including silane in the coating, anddemonstrated the pre-coated glass mat makes it possible to manufacturethe product without silane while still meeting the performancerequirement.

The inventors estimate a hydrophobic finish coating weight of 50-75lbs./MSF on top of pre-coated glass mat will provide the desiredperformance as tile backer, floor underlayment, exterior sheathing, roofboard, interior wall or ceiling. Lower hydrophobic finish coating weightwill tremendously help the manufacturing process in coating uniformity,drying, and line speed, which will need to be quantified in production.Product performance is also enhanced especially water column test. Withthe pre-coated glass mat, the process is expected to be more robust withhigher tolerance for coating imperfection.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A mat-faced cementitious board comprising: a cementitious core; afibrous mat having a first inner surface facing at least one face of thecementitious core, and a second opposite outer surface, wherein thefibrous mat comprises a glass mat substrate having non-woven glassfibers and a binder coating comprising polymer binder and inorganicfiller, wherein the inorganic filer is selected from at least one memberof the group consisting of inorganic pigment and inorganic binder, thebinder coating is present in an amount of about 40 lbs./MSF to about 165lbs./MSF, the fibrous mat having opposed first and second sides, whereinthe binder coating uniformly penetrates the glass mat substrate from thefirst side of the coated glass mat to a depth which is a fraction of thethickness of the coated glass mat; and a layer of hydrophobic finishcomposition comprising; (i) hydraulic component comprising fly ash; (ii)film-forming polymer; and (iii) an extended flow time retention agentcomprising at least one member of the group consisting of carboxylicacids, salts of carboxylic acids, and mixtures thereof, wherein thelayer of the hydrophobic finish composition adheres to the first side ofthe fibrous mat coated with the binder coating and the cementitious coreadheres to the opposed second side of the fibrous mat, and whereinpenetration of the binder coating into the mat thickness is 10 percentto 75 percent.
 2. The board of claim 1, wherein the polymer bindercomprises a member of the group consisting of acrylic polymers andcopolymers, styrene-butadiene rubber copolymers, copolymers of styreneand acrylic, copolymers of vinyl acetate and ethylene, copolymers ofvinyl chloride and ethylene, copolymers of vinyl acetate and vinyl esterof versatic acid, copolymers of vinyl laurate and ethylene, terpolymersof vinyl acetate, ethylene and methylmethaacrylate, terpolymers of vinylacetate, ethylene and vinyl laurate, terpolymers of vinyl acetate,ethylene and vinyl ester of versatic acid, and any combination thereof.3. The board of claim 1, wherein the inorganic binders are selected fromat least one member of the group consisting of calcium oxide, calciumsilicate, limestone containing quicklime (CaO), clay containing calciumsilicate, sand containing calcium silicate, aluminum trihydratecontaining aluminum oxide, and magnesium oxide containing either thesulfate or chloride of magnesium, or both, calcium sulfate hemi-hydrate,magnesium oxychloride, magnesium oxysulfate, complexes of alkaline earthmetals, and aluminum hydroxide; and wherein the inorganic pigments areselected from at least one member of the group consisting of groundlimestone (calcium carbonate), clay, sand, mica, talc, gypsum (calciumsulfate dihydrate), aluminum trihydrate (ATH), antimony oxide,microspheres, pumice, crushed or expanded perlite, volcanic ash, ricehusk ash, diatomaceous earth, slag, metakaolin, fly ash and otherpozzolanic materials.
 4. The board of claim 1, wherein the hydrophobicfinish further comprises at least one silane compound selected from thegroup consisting of: (a) silane compounds having a molecular weight ofat least about 150, (b) silane compounds having a general chemicalformula (I):(R¹O)_(m)—Si—X_(4-m)  (I) wherein R¹O is an alkoxy group, X is anorganofunctional group, and m ranges from 1 to 3, and (c) mixtures ofsilane compounds (a) and (b).
 5. The board of claim 1, wherein thebinder coating of the fibrous mat has a thickness of 0.002 to 0.050 in,the polymer of the binder coating comprising latex binder, the bindercoating being only partially permeated into the glass mat substrate suchthat 25% to 90% of the thickness of the glass mat is not coated by thebinder coating and the remainder of the glass mat is coated by thebinder coating.
 6. The board of claim 1, wherein the cementitious coreon a dry basis is 50 wt. % or greater gypsum and/or 20 wt. % or greaterPortland cement.
 7. The board of claim 1, wherein the fly ash comprisesClass C fly ash in an amount from about 50% to about 85% by weight ofthe finish composition on a water inclusive basis.
 8. The board of claim1, wherein the extended flow time retention agent comprises at least onemember of the group consisting of carboxylic acids and salts ofcarboxylic acids, wherein said carboxylic acids have the chemicalformula (II):

wherein R is an organofunctional group; wherein the salts of carboxylicacid have the chemical formula (III)

wherein R is as defined in formula (II) and X⁺ is a cation.
 9. The boardof claim 1, wherein the extended flow time retention agent is selectedfrom at least one member of the group consisting of tricarboxylic acids;dicarboxylic acids; sugar acids; aldonic acids; aldaric acids; uronicacids; aromatic carboxylic acids; amino carboxylic acids; alpha hydroxyacids; beta hydroxy acids; sodium salts of said acids; and potassiumsalts of said acids.
 10. The board of claim 1, wherein the film-formingpolymer of the hydrophobic finish comprises at least one member of thegroup consisting of acrylic polymers and copolymers, styrene-butadienerubber copolymers, copolymers of styrene and acrylic, copolymers ofvinyl acetate and ethylene, copolymers of vinyl chloride and ethylene,copolymers of vinyl acetate and vinyl ester of versatic acid, copolymersof vinyl laurate and ethylene, terpolymers of vinyl acetate, ethyleneand methylmethacrylate, terpolymers of vinyl acetate, ethylene and vinyllaurate, terpolymers of vinyl acetate, ethylene and vinyl ester ofversatic acid, and any combination thereof.
 11. The board of claim 1,wherein the cementitious core is a cement based core comprising morethan 20 wt. % Portland cement on a water free basis. the film-formingpolymer of the hydrophobic finish composition is acrylic polymers andcopolymers, styrene-butadiene rubber copolymers, copolymers of styreneand acrylic, copolymers of vinyl acetate and ethylene, copolymers ofvinyl chloride and ethylene, copolymers of vinyl acetate and vinyl esterof versatic acid, copolymers of vinyl laurate and ethylene, terpolymersof vinyl acetate, ethylene and methylmethaacrylate, terpolymers of vinylacetate, ethylene and vinyl laurate, terpolymers of vinyl acetate,ethylene and vinyl ester of versatic acid, and any combination thereof,wherein the film-forming polymer is in an amount from about 5% to about25% by weight of the wet finish.
 12. The board of claim 1: wherein thecementitious core is a gypsum-based core comprising more than 50 wt. %gypsum on a water free basis; and wherein the hydrophobic finish facingthe outer surface of the fibrous mat comprises: (i) the hydrauliccomponent comprising Class C fly ash, (ii) one or more of the followingsaid film-forming polymers: acrylic polymers and copolymers,rubber-based polymers and copolymers such as styrene-butadiene rubber,copolymers of styrene and acrylic, copolymers of vinyl acetate andethylene, copolymers of vinyl chloride and ethylene, copolymers of vinylacetate and vinyl ester of versatic acid, copolymers of vinyl laurateand ethylene, terpolymers of vinyl acetate, ethylene andmethylmethaacrylate, terpolymers of vinyl acetate, ethylene and vinyllaurate, terpolymers of vinyl acetate, ethylene and vinyl ester ofversatic acid, and any combination thereof, wherein the film-formingpolymer is in an amount from about 5% to about 25% by weight of the wetfinish, (iii) the alkoxysilane comprises an alkyl alkoxysilane in anamount from about 0.1% to about 5% by weight of the wet finish, and (iv)the extended flow time retention agent comprising one or more carboxylicacids, salts of carboxylic acids, or mixtures thereof.
 13. The board ofclaim 1, wherein the silane is in an amount from about 0.1% to about 5%by weight of the wet finish and the extended flow time retention agentis in an amount from about 0.05 to 1.00 percent by weight of thehydraulic component, wherein the silane compound has the generalchemical formula (I):(R¹O)_(m)—Si—X_(4-m)  (I) wherein R¹O is an alkoxy group, X is anorganofunctional group, and m ranges from 1 to
 3. 14. The board of claim1, wherein the hydraulic compound is at least 55% to about 75% by weightof the finish composition based on the weight of the finish compositionincluding water, wherein at least half of the hydraulic component byweight is Class C fly ash; the film-forming polymer is about 7.5% toabout 22.5% by weight of the finish composition based on the weight ofthe finish composition including water; the silane compound is 0.1-3% byweight of the finish composition based on the weight of the finishcomposition including water; and the extended flow time retention agentis 0.075-0.75 wt. % by weight of hydraulic component on a dry basis. 15.The board of claim 1, wherein the board passes the test forwaterproofness according to ANSI A118.10 (revised October 2008); whenthe board is cast as ½″ thick board, the board has a nail pullresistance of at least about 70 pounds in accordance with ASTMC1178/C1178M-13, or at least about 80 pounds in accordance with ASTMC1177/C1177M-13 and ASTM C1658/C1658M-13; when the board is cast as ½″thick board, the board has a flexural strength of at least about 80pounds bearing edges parallel to the board edge and/or at least about100 pounds bearing edges perpendicular to the board edge, in accordancewith ASTM C1178/C1178M-13, ASTM C1177/C1177M-13, and ASTMC1658/C1658M-13.
 16. A process for making the cementitious board ofclaim 1, comprising: preparing a mat-faced cementitious board comprisingthe cementitious core and the fibrous mat, wherein the mat has an innersurface adjacent to a cementitious core first surface and an oppositeouter mat surface; applying an aqueous composition comprising thehydrophobic finish to the outer mat surface to form the mat-facedcementitious board.